SECTION 5

RELEVANT UNITED STATES ENVIRONMENTAL
   PROTECTION AGENCY GUIDANCE FOR
  ENVIRONMENTAL IMPACT ASSESSMENT
             REVIEWERS

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5.     ENVIRONMENTAL IMPACT ASSESSMENT GUIDELINES
USEPA:    (05/98)

       Hie US Environmental Protection Agency (USEPA) has a responsibility for independent review
of draft and final environmental impact statements prepared by other federal agencies. USEPA also
must comply with requirements related to environmental impact assessment for its potential permit
actions for new water dischargers.  In meeting these responsibilities, USEPA has produced several
guidelines which may serve as a useful resource to reviewers around the globe. Two such guidelines are
included hi this resource manual hi their entirety, the others are available upon request.

              Sector specific Environmental Impact Assessment Guidelines: These
guidelines were developed for USEPA staff responsible for preparing Environmental Impact
Assessments (EIAs) for new source permits under the National Pollutant Discharge Elimination System
(NPDES) for facilities in specific industries.  The guidelines assist staff hi determining the scope and
contents of such EIA's and are used hi preparing, overseeing preparation, or reviewing and commenting
on environmental impact assessments for these activities:

              Fossil Fueled Steam Electric Generating Stations (1994)
              Pulp and Paper and Timber Products (1994)
              Petroleum Refineries and Coal Gasification Faculties (1994)
              *Mining (1994)
              Phosphate Fertilizer Manufacturing Facilities (1981)
              Canned and Preserved Seafood Processing Facilities (1981)
              Mechanical Products Manufacturing Plants (1981)
              Phosphate Fertilizer Manufacturing Facilities (1981)
              Rubber Manufacturing Facilities (1981)
              Explosive Manufacturing Industry (1981)
              Non-Fertilizer Phosphate Manufacturing (1981)

              This resource manual includes the guidelines prepared for Mining (5.2).

              Guidance for reviewers of EIA documents;  Separate guidelines are prepared for
              USEPA reviewers of EIAs:
             Highway Development:
             Cumulative Impacts:
             Environmental Justice:
             Pollution Prevention:
             Habitat Evaluation:
^Evaluation of Ecological Impacts (1994)
Council on Environmental Quality Handbook on
Considering Cumulative Effects Under the National
Environmental Policy Act (1997)
Guidance for Addressing Environmental Justice in
EPA NEPA Compliance Analysis (1998)

Guidance for Addressing Environmental Justice hi
§309 Reviews (1998)
Guidance for Pollution Prevention (1994)
Guidance for the Review of Environmental Impact
Assessment Documents (1993)

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               Mill! hi,   III I,,
                 Grazing on Federal Lands:    Background for NEPA Reviewers (1993)
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                 The guidance on review of highway projects for ecological impacts is included in its entirety in
                 this resource manual (5.1)
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            SECTION 5.1

EXAMPLE 1: ECOLOGICAL IMPACTS FROM
      HIGHWAY DEVELOPMENT

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EVALUATION OF ECOLOGICAL IMPACTS
    FROM HIGHWAY DEVELOPMENT
                  April 1994
         U.S. Environmental Protection Agency
             Office of Federal Activities
                401M Street, SW
              Washington, DC 20460

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EVALUATION OF ECOLOGICAL IMPACTS
     FROM HIGHWAY DEVELOPMENT
               EPA Contract No. 68-CO-0070
                 Work Assignment 2-06
                      April 1994
                    Submitted to*

                      Jim Serfis
            U.S. Environmental Protection Agency
                Office cf Federal Activities
                   401M Street, SW
                 Washington, DC 20460
                    Submitted by:

                   Mark Southerland*
                 Dynamic Corporation
                 The Dynamac Building
                2275 Research Boulevard
                 RocknOe, MD 20850

                     iUr it lit oddrctt!
                      Veaar, Inc.
                    9200 Runuey Road
                   Columbia, MD 21045

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                                      CONTENTS
 1.    Introduction	    1
       1.1    Definition of Ecological Impacts	. ,. . .	    l
       1.2    Report Format	-.	.	    2

 2.    The Need for Ecological Analysis in Highway Projects	    3
       2.1    NEPA Mandate	    3
       2.2    Federal Highway Administration Mandate	    3
       2.3    Relation of Ecosystem Protection Goals to FHWA Guidance	    5

 3.    Impacts of Highways on Ecosystems	    7
       3.1    Highway Development Activities	'.	    7
              3.1.1  Planning Phase	    7
              3.1.2  Design Phase	    8
              3.1.3  Construction Phase	    8
              3.1.4  Operation and Maintenance Phase	    8
       3.2    Types of Impact to Ecosystems	    8
              3.2.1  Destruction of Habitats .	  10
              3.2.2  Fragmentation of Habitats		  10
              3.2.3  Degradation of Habitats	  13
              3.2.4  Cumulative Impacts  ...;....	  15

4.     Ecosystem Approaches in Highway Development	  17
       4.1    Categories of Highway Development . . . .'	  17
              4.1.1  Urban	  18
              4.1.2  Suburban		  18
              4.1.3  Rural	  18
              4.1.4  Wfldland	:...''	  19
       4.2    Approaches and Ecosystem Protection Goals	'. .  19

5.     Evaluation of Ecological Impacts	;....  21
       5.1    Determining the Appropriate Scale	  21
       5.2    Establishing Ecosystem Goals and Endpoints	  21
              5.2.1  Ecosystem Endpoints	  23
       5.3    Garnering Ecosystem Information	  25
       5.4    Analysis of Impacts	  26
              5.4.1  Analytical Approach	  27
              5.4.2  Classification and Mapping of Habitats	  28
                    GIS — Geographic Information Systems	  29
              5.4.3  Characterization of Habitat Values and Impacts	  29
                    Species Characterization	  29
                    Aquatic Habitat Characterization	  30
                    Wetlands Characterization	  31
Ecological Impacts of Highways               iii            .                     April 1994

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               I,:";	 '    in'1;  " j i \ '  'ipii , ,  , . i  ' ."i 'a  " •'"  '" M'" .'  • ",t',r"'.  "r     i. i 'i  '•*' r i   li"fl.i '„ 	;	::• |i',!i «, ' ,.'  . •••'.v ',  5  •!  , '<'. « f'"1*
               I'," ;  ,  L.. :,• ;-  .I"  ,•; "" Terrestrial Habitat Characterization''. . . . :>.;N. . . . v. . . . .  . .  . • •  • .;v.	.32	
               H'} | ,   "i'';  i'f  $.4.4   Comparative M^&ods	.'........'.'..'."...'.'.  ."...... ."'. . .  .'"	.-' "'33
                      5.5   Evaluation of Qnnuladve Impacts .  . .  • •'••"• - • • •   • ••   • • •  •   •  •  •   • •  37

               r6.'    r%fitigation Measures for Ecological Impacts of" Highways"'.....'..-.	'" 39
               v'':  "   "eii"""	Eco'system Approach to Mitigation	 .. .'.	."."". . "."". .'.......•/.-.	• • •	 39
                      6.2   Mitigations for Each Phase of Highway Development	'1'	  40
               !>	;       i  •'•«;  '6,2.1^	iiPjanningiPhase  ..|........... .. .. :/ . .^. ............. . ^ 41
               ;",.  ',   .    '	".!  gjj^	Design Phase ...... I". ....". . .". .'.'•	.''..".".'.'.'... '. ........ " 44

               pi; 	''.j,i^ i, jsi'i;  '112.4'"" o^g^gQn'and Maintenance Phase .  .... I	....'.' '.'. .'. . .  .".'.'.' •'." •'." 52
                      els    Ecological Restoration as Mitigation	  55
                      •614   Mitigation Monitoring	•	  56

               :7.     'Summary of Mitigations for Ecological Impacts". .'... ..."I"........."..'.'.'	59""

               8.     Bibliography	.;.......,..:	  61
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Table of Tables
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Table 1.      - Approaches to Meeting Ecosystem Protection Goals Wmin
               Four Categories of Highway Development	  20
               Table 2.      Ecosystem Endpoints Associated with Ecosystem Protection Goals for
                          -  Use in Environmental Assessment of Highway Development  . . I . . .
               Table 3.      Hypothetical Comparison of Effects of Alternatives on Ecosystem Endpoints  ...  36
                                                                       '•, i1!,,!	i	„,;;„» ;. it MI	»,,
               Table 4.      Principal Mitigation Measures for Ecological Impacts By Phase and
               •              Setting of Highway Development  ... 1	  58

               Table of Figures.  •

               Figure 1.      Mitigations in the Planning Phase		•' • •  43
                         •	", "'i	!/ ,   •    , ; •: i •'•;., '	:;:,-? li.'.'if!:1'  Mv'-'f
               Figure 3.     Mitigations m.the Construction Phase	  -*

               Figure 4.     Mitigations in me Operations and Maintenance Phase	  54
             'Ecological Impacts of Highways                iv                                .   April 1994

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 1.     Introduction

        The purpose of this report is to provide guidance for the analysis of ecological impacts from
 highway  development activities and me evaluation of related ecosystem mitigation measures.  This
 guidance will support NEPA reviewers in providing informed comments for project scoping, EIS review,
 and 309 analyses regarding the issue of ecological degradation resulting from highway development and
 similar activities.  It is hoped that mis report wfll also be used by the Federal Highways Administration
 (FHWA)  and other federal agencies that do not have land management responsibilities as they consider
 ecological issues in environmental analyses.  Where appropriate, EPA program offices may want to
 support FHWA and other federal agencies in assessing the environmental risks of then' proposed actions
 and in developing mitigations for these impacts.

        This report builds on the  guidance provided by the earlier EPA report, Habitat Evaluation:
 Guidance for  the Review of Environmental Impact Assessment Documents, and  provides specific
 information on the ecological impacts associated with highway development.   A primary focus of mis
 report are the potential mitigations that may implemented during highway planning, design, construction,
 and operation.  Many of the degrading activities and accompanying ecological impacts associated with
 highway development are also relevant to other construction-based projects such as power generation and
 industrial or residential development.  By providing detailed guidance on both ecological analysis and
 mitigation, mis report  should  improve the environmental impact assessments for  a wide range of
 development activities.

 1.1     Definition of Ecological Impacts

        The  evaluation  of ecological  impacts has traditionally been limited  to the consideration of
 individual species, their immediate habitats, and general natural resource categories such as water and
 air quality..  Although  this approach has afforded some protection to  individual species and their
 ecosystems, it is inadequate for regional or global biodiversity protection efforts. The need to address
 the conditions of a wide range of species, and biological diversity hi general, requires an ecological
 approach  to analysis mat focuses on ecosystems.  Therefore, mis document defines ecological impacts
 as any and all changes hi the structure and function of ecosystems.
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               of concern are defined as those sensitive environments whose degradation or loss results in significant
               diminution 6f regional biodiversity (see Council on Environmental Quality 1993).  The condition of these
               ecosystems can be evaluated in terms of both structure and function and should reflect holistic measures1
               of ecosystem health or ecological integrity (see Costanza et al. 1992).
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                      While ecosystem are often classified by broad vegetation-based categories, each ecosystem is
               unique and must be evaluated in the context of its specific geographic location.  At the same time,
               alteration of an ecosystem by degrading activities must be considered hi terms of the impact on the entire
               landscape.  Therefore, an ecosystem perspective is essential fox the adequate'consideration of ecological
               impacts.  This approach requires mat the interactions of ecological components be considered, and mat
               the un|que characteristics of each ecosystem be evaluated.

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                                       Quality (1993) report, Incorporating Biodiversity Considerations
   Into Environmental Impact Analysis Under the National Environmental Policy Act, recommends an
   ecosystem approach to biodiversity conservation. Therefore, the approach and methods described hi this
   report are consistent with the increased emphasis being placed on preserving biodiversity. As evidenced
   by "thereports "of"fee Office of Technology Assessment (U.S. Congress, OTA 1987) and the National
   Academy of Sciences (Wilson1988), awareness of the immense social and intrinsic values of biodiversity
  . has increased greatly in'recent years. ' The diversity of species 'and genetic  steams 'provides a pool of
   critically important resources	for potential use 'in agriculture, medicine, and industry; the loss of wild
   plant ami animal species that have not been tested, or in some cases not yet described, would deprive
   society of these potentials. Access to genetic resources contributes about $1 billion annually to U.S.
   agriculture through development of unproved crops. Livestock and other sources of protein benefit from
   mis access as well. About 25 percent of our prescription drugs are derived from plant materials, and
   many more are based on models of natural compounds.  Native species themselves are essential as
   foodstuffs and are valuable as commodities such as wood and paper.  Marine biodiversity, hi particular,
   plays a major role in 'meeting;""tneprotein needs of the'world.  At the ecosystem level, biodiversity is
   essential to the continued provision of important ecological services, such as regulation of hydrologic
   cycles, carbon and nutrient cycling, soil fertility, and commercially and recreationally important fish and
   wildlife populations.                         .

   1.2   ' Report Format

   ';;;;;;:  [   The following sections of "this report" present the specific' approaches and methods required for
   adequate evaluation of ecological impacts from highway development.  Section 2 illustrates how the
   evaluation of ecological impacts meets existing requirements for integrated NEPA analyses.   Section 3
   discusses the many specific impacts to  ecosystems mat result from highway development activities.
 >  Section 4 provides the basic framework for addressing ecosystem conservation through evaluation of
   highway impacts.  Section 5 presents specific methods for evaluating these impacts, including identifying
^  '.^-gg'^jg"g^Qgy^jj"assessment"endpoints. Section 6 follows with specific mitigation measures that may
   fie applied to address the impacts to these endpoints. Finally, Section 7 provides a summary table of
                                     impacts in different settings.  A bibliography is included as Section 8.
               Ecological Impacts of Highways
                                                                                             April 1994

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 2.     The Need for Ecological Analysis in Highway Projects

         Traditionally, NEPA analyses of ecological resources have emphasized threatened and endangered
 (and certain  commercially important) species, wetlands (and other sensitive  aquatic habitats), and
 protected areas  (such as parks and refuges).  As the understanding of ecosystem  functioning has
 increased, more comprehensive and sophisticated ecological analyses are possible. .The recent Council
 on Environmental Quality (CEQ)  report  (1993),  Incorporating Biodiversity  Considerations into
 Environmental Impact Analysis Under the National Environmental Policy Act, illustrates me increased
 level of analysis mat is  now expected from environmental impact assessments.  Improved ecological
 analysis is also the goal of continuing efforts to strengthen the integration of NEPA considerations with
 other environmental assessment activities (Bausch 1991). Efforts  to develop methods fat cumulative
 effects  analysis  have  also been  ongoing,  and they are expected to culminate  in publication of a
 practitioner's handbook by the end of 1993 (Ray Clark, CEQ, personal communication).
 2.1    NEPA Mandate
        Section 102(2) of NEPA requires a systematic, interdisciplinary approach mat integrates science
 and environmental design into the decision-making process.  In addition, CEQ regulations require
 integrating NEPA requirements with other environmental review and consultation requirements.  Both
 of these provisions are designed to meet the basic objective of NEPA which is—to integrate environmental
 quality objectives comprehensively into planning.  The ecosystem approach, as embodied in this report,
 provides the framework for a truly integrated assessment of environmental objectives. Because it requires
 consideration of the interactions among the full range of ecological resources and focuses on the integrity
 and functioning of the landscape or regional ecosystem,  the ecosystem approach is ideal for integrated
 NEPA assessments.                                                       .
2.2     Federal Highway Administration Mandate

        There are nearly 4 million miles of roads hi the United States.  Such a complex system has the
potential to alter the natural environment hi a myriad different ways, and includes the potential for large
cumulative and secondary impacts.  The NEPA process offers federal  and state highway authorities a
unique tool for considering the full range of environmental impacts from highway development.

        The FHWA has recognized  the importance of environmental assessment in its Environmental
Policy  Statement  (EPS) of  1990,  establishing policy to avoid,  nrinhniga,  and mitigate  adverse
environmental impacts.  The statement gives the environment full consideration along with engineering,
social,  and  economic factors in project decisionmaking and stresses  the need to fully  integrate
environmental considerations into agency policies and procedures.  Of particular concern to FHWA is
the requirement to-consider the possibility of secondary and cumulative impacts  of agency  actions.
Cumulative impacts are defined hi 40 CFR 1508.7 (1978) as "the impact on the environment which
results from the incremental impact of the action when added to other past, present, and reasonably
foreseeable future actions."   To achieve the balanced consideration of these and other  impacts,
environmental concerns must be addressed in the early stages of planning and  throughout project
development.   The ecosystem approach provides  a means of identifying the  entire complement  of
resources and interactions that must be understood to adequately consider cumulative and indirect impacts.
Ecological Impacts of Highways                 3                              .      April 1994

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     i TJ:V ,:,!J!f ;!s;	I'-! '•  v-	;' ' M  *   •   ;  l",  ;!  : •' *•«••;  i "•	'Wl -J/"' 'iJT	',,v "I	ir*'1 ;1i   .!:v M  •,',  '>:• HiVf,!; Jfl  fr'j  !'.','"(
     .",!.., ;,'.	IS  i,;";!!       ' ••  'v  '•    "'  '   '•  '."   ,-   \> •'».	J	•"••'••"''•'.•Mil  i, :::"! VJ!  ,..,i"   ' >,  .'  ,  :J •; .1', f->ii • S^  ,>;	
     Is especially important when the affected environment is'largely undisturbed, while 'm human-altered
        a ta^eted' resource approach may be equally valid.  ,
               ;	-,; 	:  ; „ ;;,  ; •;	;;;; . ••	 ,  ; •  • v ••..••;,   ,• 	   ,   ,;:,;:;;"" ,;;; , :, : ,,;,;h	; •:	:;  ••  ;,„;;,„ •	• „;;	-,;•; ;. ;	;-
              nphasis on integrated assessment of environmental impacts from highway development is
              in the 1991 Intermodal Surface Transportation Efficiency Act (ISTEA).  ISTEA (U.S.
          1991) states mat                                                    .  .
                                                                         r
       "It is the policy of the United States to develop a National Intermodal Transportation System that
       is economically efficient, [and] environmentally sound...
and tii at
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        ".;. Social benefits must be considered with particular attention to the external benefits of reduced
        air pollution, reduced traffic congestion and other aspects of the quality of Me hi the United
!• ..... ' ..... :States?  ................       ' '  '  ...............      |
                                                               ........ i _   .
ISTEA  also contains provisions requiring FHWA to work with State highway agencies as never before
to preserve  and  enhance  environmental resources  while implementing transportation programs.
Specifically States are required to "... undertake a continuous transportation planning process... " which
includes statewide and metropolitan plans (including long-range plans) consistent with existing plans under
the Clean Air Act and Clean Water Act, that consider the
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        "... overall social, economic, energy, and environmental effects of transportation decisions."

        Projects related to ecosystem conservation mature eligible for federal funding under either the
National Highway System or the Surface Transportation Program include the following (emphasis added):
i1 ..... in  i    ii i • n  nun inni       i i    iir  J'lniiliii.: ' ,1  ....... r1""  T . ,!,  ""  ,",!'•" >: "j iv. : t ' '  ili1';!,1!,!!!11' „ j'°" ' "°::'' j '' 1,"11 '" '.f n, ' j''ii i11!,.!."1  "' ..... i:  "ii ..... luiii  '..
        M      _^.^> __ ^* __  •_ ___ >.i __ ^_ _ *^^ — ^ — ^ gf .. ^n _«»I«»*A^I *A «%«A«A^«^C* fimAaA iwi/lAv44iie I'lt'la ixfhi/*1i
        "... participation m wetlands mitigatkm efforts related to projects funded under this tide, which •
       may include particqjation hi wetlands mitigation banks;  contribution to statewide and regional
       efforts to conserve, restore, enhance and create wetlands; and development of statewide and
       regional wetlands conservation and mitigation plans, including any such banks, efforts, and plans
       authorized pursuant to the Water  Resources Development Act of 1990 (including crediting
       provisions)...

    .   "...  Construction, reconstruction,  rehabilitation, resurfacing,  restoration, and  operational
       improvements for 'filgnwajs (including bridges on public roads of all functional classifications),
       including... mitigation of damage tn wildlife habitat,  and ecosystems caused by a transportation
       project funded under this tide...                     .

       «... Highway and transit safety improvements and programs, hazard eliminations, projects &
       mitigate hazards caused bv wildlife, and railway-highway grade crossings."

       Implementation of such wfldlife andecosystem mitigation measures, as well as upfront, areawide
planning, can  be fecffitated  by  incorporation of  an  ecosystem approach  into  me environmental
documentation process for highways.  For example, me concepts of corridor preservation and integrated
l^usipla^                                                                           In many
cases,  a regional ecosystem approach can help unite transportation planning widi the land use and


Ecological Impacts of Highways                  4                                     April 1994
                                                              *	'"	••

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 resource management planning process of local and regional communities.  The next section discusses
 the relationship between ecosystem protection goals and the existing FHWA environmental documentation
 process.

 23     Relation of Ecosystem Protection Goals to FHWA Guidance

         As discussed previously, the FHWA has already developed substantial guidance on the evaluation
 of effects on natural resources, including cumulative and secondary impacts.  In highly urbanized and
 other disturbed environments, existing environmental documentation activities are adequate for assessing
 impacts  from highway development.    However,  federal  highway  assessments  involving largely
 undisturbed natural environments could be improved by placing mem in the framework of an ecosystem
 approach.  An ecosystem approach entails  application of princhries  of ecosystem protection (Le.,
 biodiversity  conservation) as described by CEQ (1993).  The following six principles of ecosystem
 protection are already implicit  in  many of FHWA requirements  and policies, and their explicit
 incorporation in environmental documentation can strengthen highway assessments:


 • .     Evaluate within a regional context. The "logical termini" provision in FHWA regulations and
        guidance is designed to prevent segmentation of projects and requires the use of a  "rational
        endpoint for review  of environmental, impacts".  This provision requires mat an individual
        highway project cannot be used  to force improvements hi other highway sections.  Application
        of a' regional analysis of highway development, one mat considers bom the functional utility of
        the highway and the effects on the larger ecosystem, can help ensure that the best logical termini
        are chosen. At the same time, use of a regional context for assessment can greatly facilitate the
        consultation process with other agencies and involved parties. By addressing development within
        a region, other planning and management activities are more easily incorporated. Incorporation
        of these plans is a goal of the 1992 FHWA guidance on secondary and cumulative impacts.

 •       Preserve sensitive communities and ecosystems. FHWA regulations (40 CFR 1502.15) state mat
        the affected environment  includes "environmentally sensitive features".  Consideration of the
        variety of different habitat types is essential to protecting the larger ecosystem.  Usually, natural
        resource cooperators  are  required to  point out habitats of concern other man wetlands.  An
        inventory of ecosystem (habitat) types should be conducted earlier in the planning process.  This.
        inventory would also serve to identify Section 4(f) lands (Le., public parks, recreation areas, and
        wildlife and waterfowl refuges with national, state, or local significance), as required by FHWA
        regulations.

 •       Maintain natural  habitat struct"^ and ecosystem processes.  The 1992 FHWA guidance on
        cumulative and secondary impacts stresses the need to consider indirect effects, such as those on
        ecosystem processes.  An  ecosystem approach that applies strong ecological expertise is the best
        means of evaluating indirect effects among ecosystem components. Application of an ecosystem
        perspective can also help identify important indirect effects such as the impact of exotic species.
•      Protect rare or ecologically important species. Affifa, consideration of "envJmnmftntaHy sensitive
       features"  under FHWA regulations requires  mat assessment extend beyond the  traditional
       categories of listed endangered (and threatened) species and game species to include rare and
       "keystone" (ecologically important) species. An ecosystem approach would include consideration


Ecological Impacts of Highways                  5                                    April 1994

-------
      " Ml Hi1 iliL
       iiiniii::1 IT. <	i
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                1111(11
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                                   '•'il1'	••.'
 of me full complement of species in an ecosystem, and would coordinate their protection with the
 preservation of sensitive habitat types.
ir" ,'.;• "Ill Mills; jilllll 	VXY	"!	'!'! :".	 •'):""":	•>•*': ,-.	 MlVc: :,«f '•'*: :'•  •'*!,:  " ,'>'„:,;  ,, ill'•is*  >  '*'::4\:t i1,, / mi  , ii'Mi	-	 mini
                •I	'• ,i  ,( jllli'ii'!,1  li'KJIs : :'"M ' ,
                ill11 fi  ,ir iipK '!, ii '' |M'i;	.MI,;ii , i ii;ij,iinni
                II '  !  I""  , !"i	 	"I'iiiiri1 '  ki'ijilii, ' „
                Ecological Impacts of Highways
                                                                                                         April 1994
                                                                                                          !, ' ,il ,' ,! '• '!!>' l! "' < 'IK, IV F' >'	  .,» i fill

-------
 3.     Impacts of Highways on Ecosystems

        The construction of highways can have a substantial impact on die degradation and loss of natural
 ecosystems, especially in less developed areas.   Although the actual areas  converted by highways,
 railways, and power line right-of-ways may cover only a small proportion of a region, these areas total
 27 million ac nationwide.  Perhaps more importantly, the  fragmentation of habitats caused by highway
 development is  often severe (Frey and Hexem 1985).  Transportation routes can be described as
 "disturbance corridors" mat disrupt the natural, more homogeneous landscape (Barrett and Bohlen 1991).
 In forested environments, these disturbances can cause (1) dramatic physical disruption to the continuous
 vegetative community; (2) disruption to the structure and function of habitat; and (3) impacts to resident
 wildlife, which must negotiate, tolerate, and cope with the habitat barriers.  In addition, disturbance
 corridors created by forest fragmentation alter the natural mix of habitats and species by providing
 conditions suitable for early successional plants and animals.  They replace forest trees with grasses and
 shrubs, eliminating nesting habitat for forest-interior species. While they provide dispersal routes for
 certain small Tngmmak3 they present barriers to many species.

        The scale of both the habitat conversion and habitat fragmentation effects caused by highway
 development varies with the size of the project.  The impacts  of projects also vary according to the
 environmental setting, especially the degree of naturalness in the local and regional ecosystems. In many
 cases, small individual highway projects may have little or no impact on natural ecosystems. In other
 cases, large projects can have dramatic impacts on wfldland areas (areas that are largely undisturbed by
 human activity).  Evaluations based on only a few  species or resources may be adequate for small
 projects. However, it is important to consider the contribution of small projects to the cumulative impacts
 on the region.  Although  individual road segments may cause  only minor environmental impact, the
 combined effect of the entire highway system may seriously degrade the natural environment.  In the
 same way, the cumulative impact  of several  highway systems can  seriously affect  entire regions,
 disrupting migratory pathways and other ecosystem processes. These effects may be augmented, or even
 overwhelmed,  by secondary development, i.e.,  the land conversions to industrial or residential use that
 usually accompany road building.

3.1    Highway Development Activities

       Highway development consists of four phases of activities: planning, design, construction, and
 operation.  Each of  these phases involve a number of specific actions that vary with  each highway
 development project. As described in the introduction, an ecosystem is defined to include all the relevant
natural resources affected by highway development projects. These include air quality,  water quality,
wildlife, wetlands, and all other types of natural communities. The planning and design phases of
highway development determine which ecosystems will be affected, while the construction practices and
 operation and maintenance procedures actually cause the ecosystem impacts.

3.1.1  Planning Phase           .               •                           •

       The planning phase involves all pre-design activities including the siting of the highway corridor.
Planning proceeds from the purpose and need for the project and includes consideration of all various
transportation options, potential locations, and possible basic designs. In essence, mis phase determines
the locations (and sensitive habitats) to be affected by selecting the corridor  route. Selection of me
Ecological Impacts of Highways                 7                                    April 1994

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 highway type and basic configuration and number of interchanges also contributes to identifying the
 ecosystems 'to be affected.  Both direct destruction of ecosystems and potential degradation based on.
 proximity are determined in this phase.

"34.2   Design Phase	'	'	    """	•	      "	
                                                                        ||. '  ", '.
        ThiJesign phase involves the siting of the final right-of-way footprmt and aUaspecte^
 design and within design mitigations. By selecting such highway parameters as width, slope, and type
 of crossing structures (e.g., bridges), mis phase actually determines the specific potential  impacts on
 adjacent and nearby ecosystems. While planning determines the general  areas where habitat wfll be
 destroyed or degraded (areas within the highway corridor), design decides which specific locations wfll
 be affected or avoided.  For mis reason, small-scale mitigations are most important in the design phase.
I! I |     I                            , • „':,' 1	'"' nil,''1'1 ,''!• „ ',  '  .''" , ,;i'"V ; ' ,!' ," I!")'' ', " „;!" ,'f' „ ' ' '''''''iW'l, ,:;   ,  «!!•. i'i'!i I '	I 111 ' :| l| ' i . ., ! i"'11|, II- ,,, "   ,-1','liir , fl,'!'. "!»' ,'. ,„, hf,

3.13   Construction Phase

        The constraction phase involves the vegetation removal, earth moving, and road building activities
mat actually impact sensitive habitats. Although the habitats to be affected and me types of impacts are
 already determined by the preceding phases and the basic requirement of highway construction, the
specific operation of construction activities may determine the severity of impacts such as erosion and
iisturbiicel  wile vegetation removal is inherent within the roadway footprint, excessive vegetation
 clearing can be eliminated.  In addition to physical destruction of habitat within the footprint, soil erosion
and other forms of pollution are the primary impacts in mis phase. Mitigations involving bom the timing
and performance of these activities can dramatically reduce these latter adverse impacts.

3.1.4   Operation and Maintenance Phase
       The operation and maintenance, phase includes all post-construction activities associated with the
built project, including routine vehicle traffic and roadway maintenance, as well as accidents and spills.
Routine maintenance activities include the following (Krame et al. 1985):

;•;:	*	  ^ "•, ,vl., Roadwaypaviogandpatchmg.          •'   .
       •       Roadside blading and litter collection.
       •       Vegetation management (including mowing, chemical control, planting, seeding, and
               fertilizing).    ,
       •       Cleaning, painting, .and repair of roadside structures, including curbs, drams, guardrails,

i  , Jjj	' •  '" '™  Street cleaning, snow removal, lighting, abrasives, and pavement marking.
       •       Equipment cleaning and hazardous material handling and storage.
I   III I        1111   III*  *                         , „                                . •  	:	

Although similar in nature to construction impacts, the pollution effects of this phase are long term. Best.
management practices are the principal mitigation measures for these impacts.
fl  " ,'•'. (""\'tW .;* "I"'.;!",-	', •   ||" ' ;::';  .,i'V.r  [',  _"!  ,!  '" '	-.'  '       '     '      'I     i  : ,'       ,  _ •   >:
33  "	Types of Impact to Ecosystems

       A completed highway project necessarily includes impacts from all of the phases described above.
Genericaily, highway development  can be said to affect ecosystems, and their values and functions,
through* me! following stressor processes:


Ecological Impacts of Highways                 8                                     April 1994

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               Alteration of topography.
               Vegetation removal.
               Erosion, sedimentation, and soil compaction.
               Dehydration and inundation. •
               Acidification, salinization, and wanning.
                           tOXICIty.
               Noise and visual disturbance.
               Introduction of exotic species.
               Direct mortality from road kills.

These stressor processes can result in the following effects on ecosystems:

               Direct mortality of resident species.
               Physiological stress and .decreased reproduction.
               Disruption of normal behavior and activities.
               Segmentation of interbreeding populations.
               Modified species interactions and alien species invasions.

        Although highway development shares these effects with other human activities that degrade the
natural environment, highways (as well as powerline rignts-of-way and other transportation routes) have
unique impacts associated with their linear form. Within forested landscapes, highways act as concave
corridors, areas that exhibit lower vegetation heights than the surrounding habitat matrix (Gates 1991).
In agricultural and some rangeland landscapes where dense vegetation is encouraged along the roadsides,
highways may act as convex corridors. These highway corridors may function as (1) specialized habitats,
(2) conduits of movement, (3) barriers or filters to movement, or  (4) sources of effects on  the
surrounding habitats (modified from Forman and Gpdron 1986).  Exactly how the corridor wOl function
depends on the condition of the larger landscape, not simply the habitat adjacent to the corridor. For
example, a highway corridor in a forested landscape will function differently than a corridor  bordered
by forest, but which exists within a landscape dominated by agricultural land.  Highway development is
also unique hi its facilitation of secondary development.

       The direct, indirect, and cumulative impacts of highway development can be grouped into three
general categories:

        1.      Destruction of habitat (resulting in the elimination of certain  habitat types and men-
               replacement with non-natural uses or with specialized semi-natural habitats)

       2.      fragmentation  of habitat (resulting in the loss of habitat integrity through the creation
               of barriers to species  and ecological processes).

       3.      Degradation of habitat (resulting in the loss of habitat  integrity through disturbance of
               resident species, contamination with pollutants, alteration, of natural processes, and
               introduction of exotic species).
Ecological impacts of Highways                 9                                     April 1994

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            , '•  PI1;  '. v'!""*$?  !;!   ; ••''>•>iii'^:'::  '          '          '

'. li'l!"!1:  ' : '  i*,!"  *   I'"1-''!  !   '	r.i vJl!1'* ' 'iWI  	Li"1 ,  .i.-1 • !' i»S.',.* "ll!
if   	!   in      M    i:.M	.,11  ;:ii  .;; •,-!	tiWti  ••       .   i	  	  ...
!	      ••:  3.2 JL  Destruction of Habitats	       	       r	
I,; ii 11          ji  iiiiii" ' i: .. •""	iii'  " i:	,  ,	,,	, I,,	,   ,  .,	 ..,		„,	i	
             ', 	    , 	 	<	  '	"I!	
                      The most direct effect of highway development on ecosystems is the destruction of a natural
               habitat through its  "conversion"  to  a transportation land use or "right-of-way"'".   Although natural
               vegetation may be preserved within the right-of-way, the original natural characteristics of the land are
               eliminated within the payed area and adjacent roadsides.  The clearing of vegetation (trees,  shrubs,
               grasses) and accompanying leveling operations (mat destroy the original topography and soil profile) are
               the principal changes. In some cases, the natural vegetation may be replanted while hi others different
               species are planted and the habitat values modified.   In wetland environments, road construction may
               require fflmg and Draining operations that destroy wetland habitats.  In aquatic environments, flow
               alteration (via damming or channelization) may eliminate habitat.  Dredging, filling, and draining required
i' SJII"!'   I. ''.''I1!:  :	:"!	l;l1 -1',™ ''  '""'	••	 '"'3	"	y	;	-	•-_ ' „>"" *_" T_*Z.V         	    	    	     	
f! jl!  .  • , .;,*
 b''roadl''constoctSn also" desEby aquatic habitat.

             conversion of forested land to
 a|ppg the roadway "with grassy or shrubby vegetation.  These early successional areas provide additional
 habitat for species' such as Brewer's and red-winged blackbirds (Adams and Geis 1981). These and other
 birds are likely attracted to suitable nesting, perching, or feeding sites. Interstate rights-of-way have also
 %8n P&PJW to, tl'BSf*' sig"ffleant populations of small mammals (constituting 17% of wildlife mortality).
 Trapping data indicate that right-of-way habitat and its accompanying edge are attractive not only to
 grassland species but also to many less-habitat-specific species. Examples include, in the Southeast— the
 eastern harvest mouse, white-footed mouse, and meadow vole; hi the Midwest—the prairie vole; and in
 the Northwest— the vagrant shrew,  Townsend's vole, and  California vole (Adams and Geis 1981).
 Although certain species benefit, the creation of homogenous modified early successional environments
 negatively "'affect fggionai ecological diversity by replacing complex coevolved systems wim common
 species and simplified systems.  In the case of .forest environments, this conversion represents a decrease
 in the structural diversity. Universally, the removal of vertical habitat structure reduces the diversity of
" species!  Staicoiia! d^elfsn^'piovides' more microhabitats (e.g., nest sites) and allows for more complex
 species interactions (e.g., avoidance of predation and partitioning of foraging space).

        Tn stmiTnary, both the construction of paved roadways and me removal of vegetation from the
 right-of-way result hi the destruction of natural environments and the loss of habitats.  The impact of
 these losses on local and regional ecosystems varies wim the habitats destroyed.  Although all habitats
, contribute to ecosystem integrity, those mat are rare .or play critical ecological roles in the landscape can
 be designated as "habitats of concern" and given special consideration. A discussion of regional habitats
 of concern is available hi the EPA Office of Federal Activities (OFA) report (Soumerland 1993), Habitat
 Evaluation: Guidance far the Review of Environmental Impact Assessment Documents.

 323.  Fragmentation of Habitats

        In general, highway development rarely eliminates entire habitat types, but instead destroys part
 of a habitat, leaving other areas intact. In most instances mis local habitat destruction is better thought
 of as .habitat fragmentation.  Such fragmentation is the principal cause of me loss of "area-sensitive"
 sgpecies (Harris '1984) and is considered the most  serious threat to biological diversity  (Wilcox and
 Murphy 1985, Harris 1988).  For example, fragmentation on a broad geographic scale has been shown
 to result in declines of songbird species (Whkcomb et al. 1981).   Specifically,  studies hi Maryland,
 Michigan, and Oregon have shown that me occurrence of most forest-dependent species is correlated with
  ill!	\' « • ) ,"
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  forest size, and that contiguous forests of 100 to 300 ac are needed by long-distance, insectivorous,
  neotropical migrants, such as flycatchers, vireos, and wood warblers (Terborgh 1992).

         The consequences of habitat fragmentation (Hards and Atkins 1990, Hunt et al. 1987) may
  include the following:

         •      Erosion of genetic diversity and amplification  of inbreeding  (Le.,  risk  to
                sedentary  species from random variation in demographic and genetic variables
                when isolated).              .

         •     .Increased  probability  of local  extinction from small population sizes  and reduced
                likelihood of reestablishment (because immigration is inhibited by barriers).  -

         •      Extinction  of wide-ranging species (e.g.,  wolves, black  bears,  panthers,
                manatees).

         •      Loss of interior or area-sensitive species (e.g., sharp-shinned hawk, Cooper's
                hawk, Swainson's warbler, red-cockaded woodpecker).            .

         •     Increased abundance of weedy spedes (regionaUy distinct communities give way
               to globally homogeneous ones).

        As discussed under the destruction of habitat, highway rights-of-way may be converted to a
 modified earlier snccessional habitat depending on the width of the corridor.  Bom wide and narrow
 corridors can act as effective barriers to the movement of anhn^ effectively isolating habitat patches
' and subpopulations. In addition to the effect of distance, wind-funnelling can prevent the migrating and
 dispersal of invertebrates and plants across corridors (Sheate and Taylor 1990). The many discontinuities
 associated with roadways and traffic also contribute to  the barrier effect, principally the break in
 microclimate (temperature, humidity, and evaporation), instability of the vegetation (due to mowing and
 spraying), vehicle emissions (noise, dust, headlight illuminations, car exhaust, increased salinity in soil,
 vegetation, and ditches), and direct road kOls (Mader 1984).  In fact, the simple contrast in. habitat
 conditions characteristic of edges often acts as barrier to the distribution and dispersal patterns of bom
 birds and mammals (Thomas, Maser, and Rodiek 1979).

        The most obvious barrier effect is direct mortality of annuals attempting to cross  the highway
 corridor mat result from collisions with motor vehicles.  Millions of animals are killed annually on
 highways (Leedy 1975).  Road kills may represent  a critical mortality factor for large wide-ranging
 species mat can often avoid direct impacts of other development activities (e.g., key deer in Florida).
 Annual road-killed animals are significantly correlated with average vehicle speed (Case 1978).  In an
 extensive study of highway impacts on wildlife, Adams and Geis (1981) observed mat 76% of road
 wildlife mortality occurred on interstate highways and mat  roads appeared to act in a density-dependent
 manner, predominantly killing those species attracted to roadways. Species killed in greatest numbers
 included meadowlarks, indigo buntings, field sparrows, red-winged and Brewer's blackbirds, deer mice,
 several vole species, and rabbits.
Ecological Impacts of Highways                 n                                     April 1994

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        Adains and Geis (1981) also found many species reluctant to cross highways.  Shrews are a
 disturbance sensitive group that rarely enter rights-of-way; other sensitive species include the golden
 mouse, pinon mouse, dusky-footed wood rat, California red-backed vole, and brush mouse.  In June
•"surveys, salamanders did not readily cross interstate highways, and were not attracted to right-of-way
 habitat/ Turtles, frogs and toads, and snakes were common road kills. Foxes, raccoons, skunks, and
 Coyotes 'appe^j[^0 snun interstate rights-of-way even though a substantial small mammal food resource
 is available mere. Elk tended to avoid habitat adjacent to interstates and forest roads. Roads did not act
 as a critical barrier to. deer, but roadside hunting and dogs affected deer distribution.
        Early fSd data from Oxley et al. (l§74) suggested that smaU forest mammals were reluctant to
 yenmre daE road surfaces where the distance between forest margins exceeded 20 m.  Burnett (1992)
 Mader (1984) extended the roadway barrier effect to wandering insects by determining that forest carabid
        ivoli "imstaHe habitat conditions.  He also  demonstrated  that mice species  will adjust their
^territory boundaries to avoid roadway corridors.
i™ jj,11 !,', ' "*;;,! ....... ;, ' " "i"1  l'lil!±l! ', ,11 ........ "''!'!!!" "  ........ „,,' ";,; ',;,  ,   ,'  ','"  .........    ,,„    „ , ,  ' ................ ......   , ,,ji   "  ,,, ,        , ,„ ............... , ...... ,'
J ......... ™; • |J "' 'J m \"'r "n _";[,,  !„",',,, ...... , ', i ,, ..... "" , " I ,!|,' i !,,!„, ,„' ,  „  '! ' ' ,' "  , ,",' |'» |p ' ^ ........ ^   " |'|i|||-  ^ ^ "»j ..... ^ " | "•  ^ J™ '^ '" ^ • |||1'" 'i""m"\"' : ...... ^a' ; ' ^ """ '""-^ ,,",' ' " , 'j,!, ,  , ..... ' *|, ,,, ' '  ,'„;",,
        Because the majority of species respond to corridors as an activity filter, reducing activity with
?liStance"to ......... me ........ coSIbr; ...... changes "in corridor vegetation  can reduce me effectiveness ..of me fitor by.
 softening me edge or creating "pores".  Edge permeability increases as the contrast between adjacent
j^g-^^.™^-^..^^ Godron 1981). even smaU changes hi edge permeability may have large
 impacts on animal movement across patch boundaries (Buechner 1987).

        Bom jo'JJ^i and rtonforested environments can be disrupted by fragmentation due to highway
 consiruction. However, the dense canopy structure of certain shrublands may be most severely impacted
 by fragmentation.  An example is the fragmenting of pocosin wetlands and uplands in me Southeast.
 Because of the scale at which many pocosin inhabitants move, highway development can effectively
 isolate much of me pbcosm fauna.
                                                                       i.'.....,.
        Barrier effects  are not limited to terrestrial habitats and may have extreme consequences for
 migratory fish species where highways have diverted streams or .constructed impassable  culverts.
 Upstream passage is a particular problem for anadromous fish such as salmon and shad that must travel
;long"(tistances; to reach natal spawning grounds. Passage of anadromous fish at large dams has received
 consWerable attention  tough research and the construction of fish ladders and lifts  (Bell  1991).
 Ironically, culvert barriers associated with highways often occur at the end of spawning runs just below
 Spawnmg grounds, thereby negating passage achievements downstream. Even small barriers can act as
 blockages near the end of the spawning run when me passage capabilities of  anadromous fish  species
 may decline. In addition, resident fish can be adversely affected by stream blockages, as in the  case of
 Hout;-pjke, and grayling mat migrate upstream and downstream during their lifecycle in search of habitats
 for spawning, rearing,-or shelter.
I III i     i   i iiiiin  i i          MI                   H'vi .,:>,, H':r  i, 'f v  r ; i,J,hi,jii	"i ;:\'\",\	  h "iiiini iLrjiin,,1! .""fiin,, ,   'i|i*i," •• !M, i  •!'  . !, 'iHWviiHiK ,
        The success of fish passage is principally dependent on the swimming ability of the fish  and the
 hydraulic conditions of the modified stream segment.(Baker and Votapka 1990). Swimming ability varies
 with the size and species of fish (Bell 1991). Passage problems include:
                                           .
        •      Vertical barriers.
        •      Water velocities that exceed fish swimming ability over prescribed distances.
                                       i                       iii
            I II  llll 111                    II                   I      III         II                       I

 Ecological impacts of Highways                12                                    April 1994

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        •      Low water depth.                                                    .
        *    '  Icing and debris blockages.

 In addition, culverts can limit passage through changes in water temperature,  water pollution, and
 darkness that conflict with behavioral requirements of the fish (Baker and Votapka  1990).  Another
 important factor is the relation of these modifications to annual hydrographic and seasonal time of fish
 passage for all species of concern.  For example, even closely related species may have different
 spawning times (e.g., brown trout spawn in the fall in Montana where rainbow trout spawn in the spring).

 3.2.3   Degradation of Habitats                       .

        Degradation of habitats specifically refers to a decrease in the health or ecological integrity of the
 "intact" habitat.   In the  case of highway development, mis degradation is closely associated with
 fragmentation and. what many researchers call the "edge effect".  This edge effect can be viewed as a
 reduction in habitat integrity at the boundary of a highway corridor caused by disturbance, contamination,
 or other degrading factors  mat extend into  the natural  habitat.   In  addition to direct toxichy and
 behavioral effects on resident organisms, this degradation includes the alteration of natural processes such
 as water flow, fire regime, and species interactions.  Biological invaders are a particular problem along
 roadway corridors that can seriously degrade natural systems by modifying species interactions.

      1  Sheate and Taylor (1990) state that the vulnerability of woodlands to degradation from motorway
 impacts is dependent upon the size of the woodland; mat small woodlands will tend to be susceptible to
 physical impacts, whereas larger ones will be more vulnerable to qualitative change. Direct edge effects
 on ulterior  trees include  temperature effects of aspect, wind-funnelling "jet" effects, potential root
 starvation from  lowered water tables adjacent  to cuttings, increases  in evapotranspiration,  and
 susceptibility to wind-blow.

        Effects of disturbance associated with forest edges has been well documented for many mammal
 and bird species.  In particular, large, mobile carnivores such as mountain lions and grizzly bears require
 extensive tracts of undisturbed habitat  (Wilcove and May 1986).  Ferris (1979) found mat bay-breasted
 warblers, blackbumian warblers, blue jays, and winter wrens avoided forest edges along highways and
suggested mat noise created by vehicular traffic, rather man vegetation differences, render the forest edge
unsuitable for breeding.  Recent research indicates mat increased edge effects result in less "secure"
habitat for nesting birds (Temple 1986) and a much higher incidence of nest predation and parasitism
 (Wilcove 1985, Laudenslayer 1986).

        Because detrimental edge effects may extend 600 m into a forest, Wilcove (1985) concludes mat
more than 100 ha of contiguous forest are required for forest-interior habitat.  Van Der Zande (1980)
found empirical support for Veen's (1973) conclusion that disturbance effects greatly exceed right-of-way
widths and may extend 500 to 600 m  from quiet rural roads and 1600 to 1800 m from busy highways
in the Netherlands. Terborgh (1992) estimates mat areas as large as 15,000 ha may  be needed to provide
safe havens  from nest parasites such as brown-headed cowbirds that fly up to 7 km in search of host
nests.
Ecological Impacts of Highways                13                                    April 1994

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  i	s	
.ti!'|: .I'll' iii il'nlii n: .'it*
• iil'I:
      i " Illlu'" i illi *
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        .'ft*
  (Ill I
  ::.','	:' :	Pollution	
            •	rfn

      .'iChemical contamhiation related to highway development results from ah- or water pollution during
  construction and operation and can be a significant cause of habitat degradation, especially in aquatic
  environments.  Although'toxic effects may be the most severe, conventional pollutants and other effects
 s m|"33st in	grei^^fre^eng^^ffl^^extent.	For example, soils are degraded through erosion or sofl
  compaction while elevated temperatures may damage adjacent vegetation.  Rivers amji streams can be
  degraded by siltatipn and salinization from deicing activities. In general, highway construction parallel
 i" to	streams provides greater opportunities 'for adverse effects man perpendicular arrangements mat result
  in stream	crossings.	Underground water sources and	meir contributions	to ecosystem integrity can be
  degraded	by	runoff and	hazardous  material spills that contaminate aquifers.  Where highways cross
 permeable sandstone	and limestone, they introduce the possibility of fractures mat can contaminate or
               111 ..... ;
                        ' ii/lii; ',,.» ..... Ill
        	 	',"'!:;  i,wit Oii'v/V'*:,!1'!.	.:•.,'	«*	!!?
                   v  Disruption of natural processes
                      In addition to disturbance and contamhiation effects, highway development can seriously degrade
              habitat through the alteration of ecological processes;  These processes include natural hydrology, fire
              regimes, animal migration patterns, and competitor and predator-prey relationships (including the effect
              of exotic species). By creating barriers to natural water flow, highways can degrade aquatic systems,
              wetlands, and terrestrial environments.  Natural stream flows are usually maintained by the construction
              of bridges or culverts, although barrier effects and local losses of natural aquatic habitat may  result.
              Wetlands are more problematic.  Natural drainage patterns are easily disrupted in the saturated soils
              characteristic of wetlands (McLeese and Whiteside 1977).  If a surface highway runs perpendicular to
              the path of water transport,  even precise construction of drains  and ehanneig may  not prevent sofl
              compaction from lowering the water table and eventually draining downfiow wetlands (Sheridan  1988).
              On the upflow side, ponded conditions can lead to tree death.
             	ill,:	i
                                                                   iiP	iii IV
       The adverse effects of road building on natural hydrological patterns are especially deleterious
for riparian habitats. In arid environments, riparian areas make up 80% of available wildlife habitat and
support the majority of endangered species  (Johnson 1989).  The maintenance of natural flow patterns
in perennial and intermittent streams is critical to these unique habitats. Impacts on riparian areas from
highway development include the following (Terrene Institute 1993):
                                                                                                            (fflff
              Ecological Impacts of Highways
                                              14
April 1994

-------
        •      Acceleration of runoff, increasing flood peaks, erosion, and downstream sedimentation.

        •      Dewatering of riparian areas as gullies are created by concentrated flows.

        •      Decreased volume and duration of base flows, causing streams  (including former
               perennial streams) to dry up earlier in the year.

        •      Shifts at plant composition from riparian species to drought-tolerant invaders or upland
           .    species.

        •      Loss of habitat for riparian-dependent wildlife species.

        Suppression of fire is a common impact on virtually all humaoHise lands. Land use practices are
the major factor suppression natural fire regimes, although highways may act as unnatural fire breaks in
some areas.  Many plant communities require a natural periodicity and intensity of fires to maintain men*
typical species composition.  Where highways combine with land use practices to reduce the frequency
of fires, the accumulation of flammable material may result in less frequent, intense fires mat degrade
native habitats.

        Natural animal migration patterns, as well as the relationships among competitors and between
predators and prey, are an essential part of ecosystem integrity. While some species (such as birds of
prey) may benefit from access to a new food source, many less adaptable species are adversely affected
by the presence of new competitors or predators. The greatest danger to these processes is posed by the
invasion of non-native, or exotic, species.  Highways can act as movement corridors for exotic animals,
or even provide intentional or unintentional transport in vehicles.  Non-native weeds are a particular
problem for highway rights-of-way where the inevitable transport by wind and tires is often exacerbated
by the intentional planting of exotics. The magnitude of the problem has prompted an interagency white
paper for the Federal Coordinating Committee on Science, Engineering, and Technology (FCCSET) mat
calls for mamtaming a Federal Interdepartmental Committee for Management of Weeds (FICMW). The
goals of this  committee would be to develop a Federal  Land Weed Management Policy that would
strengthen Federal Agency Manuals, review  current agency policies for effectiveness, contribute to
national legislative proposals, and create prioritized coordinated treatment efforts (Anonymous 1993).

3.2.4   Cumulative Impacts

        As mentioned earlier, .highway development differs from  other degrading activities in the
proportion of its effects that can be attributed to cumulative impacts. The effects of highway development
accumulate when different road segments or highway systems overlap in space or time. The principal
effect of the cumulative impacts of highway development is increased habitat fragmentation.  As habitat
patches become smaller  and more isolated, species mat depend on them become less able to find mem
and to maintain populations in mem.  The National Research Council (1986) described these decremental
effects  as "nibbling". The combined effect of these cumulative impacts may exceed the sum of each
impact or even create a qualitatively different effect on the ecosystem. For example, individual highway
projects may not affect forest-interior bird species, but when several  projects provide enough habitat to
sustain brown-headed cowbirds, nest parasitism may completely eliminate forest-interior species from that
habitat.
Ecological Impacts of Highways                 15                                   April 1994

-------
urn-*.?r"'f	i":
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i:  nuiii !IL k i '<" ir in;,'
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  '
                             l1!':'' " s IF * MV . \t • ;:» s ....... iiiiss :?, ..... is
                             N1!!  lii, , |h'' '   : ,' ' „,„ ...... ', Iii|ii><: ..... i!ll|ii|ii!'>!l»! i:"' TI|
                               Mi '!• • ;"' ^: I
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                                                                         11V;!
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                                                                                                              .! i r'	• • i '.'I  . lj •
                       jjjggg g^jg^jjg jj^y ^e augmented, or even overwhelmed, by secondary development, i.e., the land
                         s'tb industrial or residential use that often accompany road building.  Capacity improvements,
               additional interchanges, and new location construction have greater potential for secondary development
               than upgrades of existing faculties.  Creating new access to undeveloped locations can have the greatest
               impact, if other economic conditions are favorable. In fact, demand for increased capacity often creates
               a highway that, in turn, increases the  influx of secondary development and recreation, thus creating
               demand for yet more increased capacity (Sheate and Taylor 1990).  It is important to note that the
               promotion of economic development in depressed areas through infrastructure improvement is often the
               purpose of a highway project.
          	  '   "  	  "	""	I	  	 '	
                      The FHWA recognized the importance of considering cumulative impacts in its  1992 Position
1. iLihi :-ii;" jiri >	i  Paper  on	secondary	and	cumulative Impact	assessment.	In mis	guidance,  FHWA	proposed	mat	
1 ;!l!!|:|!<:'!ll<;: arj	Ijj^jjfi -"i  enviromnenial assessment focus on me functional rdationships of rescue        larger systems because
     ,i,,. .,,,,,, ., ,,,,,1, ^ ^ |-g«|«|, gggg™ Sss3icM.ted "with "g^JSjf^jyj ''fajQwfe;	
     ],;|:,,
              ,      ,,,            ,.    ,           ,.   .
              Secondary and- cumulative consequences  are
                        1"
                                                                                               ,. .   .....   ,.    ,„ ........... ....... .
                                                                                    by impacts  to  environmental
                                                                                                 '  '  .......................... '
                              Since the resource functions may be removed in both distance and time, secondary and
                              cumulative consequences to  the larger system may likely be "invisible" to normal
                              environmental studies that examine only the immediate influence of an isolated project
                                                                                                                        ^ ..... MI
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                I!* i'  ii'i;  »i	i; 'ik1 ' ;,,ni
-------
4.     Ecosystem Approaches in Highway Development

       The emerging disciplines of landscape ecology and ecosystem management are providing new
insights into  potential approaches  for assessing ecological impacts, including those from highway
development.  Although mis research has not yet produced definitive methods for ecological impact
assessment, some general principles for ecosystem (or biodiversity) conservation are becoming accepted.
The recent report of the CEQ, Incorporating Biodiversity Considerations into Environmental Impact
Analysis Under tfie National Environmental Policy Act (1993), provides the following eleven general
principals of ecosystem management:

       1.     Take a "big picture" or ecosystem view.

     •  2.     Protect communities and ecosystems.

       3.     'Minimize fragmentation.                                                       •.
              Promote the natural pattern and connectivity of habitats.

       4.     Promote native species.
              Avoid introducing non-native species.                                      -

       5.     Protect rare and ecologically important species.                             •     .

       6.     Protect unique or sensitive environments.

       7.     Maintain or mimic natural .ecosystem processes.

       8.     Maintain or mimic naturally occurring structural diversity.

       9.     Protect genetic diversity.

       10.    Restore ecosystems, communities, and species.

       11.     Monitor for biodiversity impacts.
               Acknowledge uncertainty.
               Be flexible.                                                             -

4.1   Categories of Highway Development

       Each of these principles has implications for assessment and mitigation of ecological impacts
caused by highway" development.  However, the applicability of each principle wfll vary with the
conditions surrounding individual highway projects.  For example, fragmentation will likely be less
important in highly urbanized settings.  Therefore, it is useful to consider assessment of the ecological
impacts of four distinct categories of highway projects:

        •      Urban
        •      Suburban
 Ecological Impacts of Highways                17                         •          April 1994

-------
                                                                                                            II," II
                                                                                                               I'll	
                               Rural
                               Wildland.
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                                 .
             way development in urban settings may have little impact on sensitive habitats, or natural
            of any land.  Often, road construction affects only previously developed areas and may not
 have even indirect effects on natural habitats.. However, in some instances, urban highway construction
 will have substantial impacts on natural water bodies or other habitats existing within the urban matrix.
 Destruction of these habitats can occur if new roadways are built on any of me few remaining natural
 areas.  Fragmentation is	of lesser" importance, because natural- habitats  are usually already isolated by
 urban development.  The principal impact of highway development in the urban setting is habitat
 degradation. River habitats running through urban areas may receive greater loadings of pollutants from
 runoff during construction or normal operation of the highway. Other impacts include adverse effects
 on urban trees and wildlife.	Direct mortality of certain species may increase through road kills, and	air"
 pollution	may damage terrestrial	vegetation.	Deposition of airborne	contaminants may	also	degrade
 aquatic vegetation and fisheries. Because of the extensive development  hi urban areas, cumulative and
 secondary development impacts from highway development are usually minor.
 iii!	I';"'1	'.•*.,   	II	I	I,   '   	      I    i  I     *         	3if ••*«&•	,N	',,"!	Bit!'1'1'! V;  '•;;; '  ;
               •111, 'I).,,!:, ,	'	'   111 I   111 III
               4.1.2   Suburban
                                                                                                          11 I1 	"l|l .'"BIU 'n'llll' In 'ill , ,, '	I,
                                                                                                          .1 ;,;,ii	jflaf lilt1«" ,-i	".'"-a
                       As hi urban areas, highway development hi suburban settings can still adversely affect vegetation
               and wildlife mat are well adapted to human-altered habitats.  Perhaps more important are the impacts on
               species less adapted to urban conditions, which try to move among pockets of natural habitat within the
               suburban matrix. For this reason, fragmentation can have a severe impact on suburban habitat. While
               high levels  of ecosystem functioning are rare in urban environments, suburban areas may  maintain
               substantial habitat integrity if a considerable undeveloped area remains and natural habitats are connected
               in a planned or de facto system of natural areas or greenways. Creation of additional highways can sever
               remaining migration corridors and further isolate species.  Pollution  from air emissions and roadway
               runoff are important, as are the higher levels of roadkflls.  The introduction of weedy or pest species is
               a special problem in suburban areas, where native species are surviving in unnaturally small habitat areas.
               Cumulative nnpacts of highway development hi suburban areas can be severe, and secondary development
               often follows	road	construction and other infrastmcture improvements	in this high growth setting.	
               4.13  Rural
                      i ........ .r
                                                                                                           „	; ,i,	ill	/,:,
1,1     Rural areas are	characterized by less	land conversion to residential,	commercial, and industrial	
uses. Additional highway development may have a greater proportional impact on rural areas man on
suburban or urban areas,'  although this is reduced in heavily agricultural  regions.  In most rural
environments, significant areas  of natural habitats remain..  Although they may be fragmented by
cultivated fields, grazing pastures, and commercial timber	lands,	natural	habitats are more likely to be	
impacted by highway development hi rural settings man in suburban or urban ones.  Except hi areas of
monotypic cropland and timberland, rural areas contain a greater variety of species man do urban and
suburban settings.  Many  rare  and regionally important species  may be at risk.   Destruction and
degradation of these habitats usually accompany any highway development mat is not confined to existing
agricultural hind.  Degradation of hydrological processes, as well as nutrient and energy cycling functions
||e more important hi rural environments. Fragmentation is perhaps the most important impact, serving
Illif'"::]":: ,:    '• •  ' '-•
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of Highways
                                                              18
                                                                                     April 1994
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-------
 to sever migration routes that continued across agricultural lands  and other undeveloped regions.
 Cumulative impacts may be a major factor in rural environments where highway development is provided
 as a stimulus to secondary development and ultimately local economic enhancement.

 4.1.4  Wildland

        WHdlands are landscapes  largely undisturbed by human  activity.  Highway development in
 wildland areas differs substantially from mat in rural, suburban, and  urban settings.  Rather man
 contributing to the cumulative impacts of a suite of development activities, highways are often the only
 major impact on wildland habitats.  Where secondary development does follow highway development (as
 in second home development), alterations to the natural habitat are almost always severe.  The intricate
 ecosystems found in wildlands possess far more sensitive species and  maintain a larger suite of natural
 functions man in previously developed areas.  In addition to water, nutrient, and energy cycling, fire
 regimes in wildlands can be disrupted by highway development.  Destruction of habitat (where virtually
 all areas  are sensitive), fragmentation of habitat (where contiguous  natural areas are the rule),  and
 degradation of habitat (where species are more sensitive to disturbances such as noise) are all important
 factors in wildlands.

 4.2    Approaches and Ecosystem Protection Goals

        Hie following table illustrates approaches to attaining ecosystem protection goals within each of
 the four different categories of highway development With the exception of urban environments, most
 of the goals are applicable to virtually all highway development projects.  The specific approaches may
 differ among categories, and are not limited to the examples given below.
Ecological Impacts of Highways                 19                                   April 1994

-------
                                                                         ,"!:  ''I!,	ii «;:;
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                               Approaches to Meeting Ecosystem  Protection Goals Within Four  'Categories	of	"
                              	iway Development	
jii< iiiiiiHiiiniiD : ,'!iiii;!'i  in i!;;:
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s-^—
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Plant native species
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Cctegories of Highwmy Derdopment
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Control exotic pests
populations
Protect wetlands and
riparian zones
stream flows
Maintain diversity of
natural vegetation

Restore riparian areas
Monitor landscape
Rural
Protect witeabeds
Maintain local

cosxidoei
Tjniit 
-------
  5. Evaluation of Ecological Impacts

     FHWA mandates clearly require consideration of direct, cumulative, and secondary highway impacts
  on ecosystems.  This can be accomplished by using the ecosystem approach presented in the CEQ
  biodiversity document (1993)  and discussed  in this report.   The steps required for habitat impact
  assessment are basically those of traditional FHWA assessment with me incorporation of a landscape
  perspective and  the identification of specific ecosystem endpomts.  In addition, many of the  same
  analytical tools currently used in environment assessment can be modified to include me improved land
  pattern analysis that can be achieved by using geographic information system (GIS) technology.

     Evaluation of ecological impacts from highway development requires both scoping and analysis.
 Included in scoping are the determination of the  appropriate scale of analysis, the setting of specific
 ecosystem goals  or  endpomts, and  the gathering  of information.   The analysis phase involves
  consideration of the impacts on individual ecosystem endpomts and quantification of specific effects where
 possible.

 5.1    Determining the Appropriate Scale

     Scale is a central issue in the ecosystem approach.  The appropriate boundary for  highway impacts
 is  one mat ensures adequate consideration of all  resources that are potentially subject to non-trivial
 impacts.  For some resources, mat boundary can be very large.  Hydrologic and atmospheric transport
 of emissions and surface runoff can affect distant reaches of the watershed.  In addition, barriers to
 migration may affect populations on the  regional scale.   At the other end of the spectrum, habitat
 protection also  includes identifying and avoiding small sensitive areas, such as rare plant communities.
 Determining relevant boundaries for assessment is guided by informed judgment, based on the resources
 potentially affected by an action  and its predicted impacts.  Although in some cases ecological impacts
 may be limited to the highway  corridor (e.g., 300 feet in width), impacts wfll  often extend to the
 watershed or ecological region (via indirect and cumulative impacts of additional road  construction and
 secondary development).                                                                  .

    Separate jurisdictions and competing missions may make it initially more difficult for federal and state
 highway departments to engage hi cooperative ecosystem management with other agencies.  However,
 clear benefits are to be gamed from sharing expertise, technical capabilities, and information; such
 sharing will lead to unproved environmental decisionmakmg.   Highway agencies need not sponsor
 regional ecosystem planning efforts to benefit from them, however inclusion of transportation planning
 into regional land use planning should be done as early hi the process as possible.  Early consideration
 of ecological issues in the highway development process may be the most important factor hi ensuring
 the environmental success of projects.

 5.2     Establishing Ecosystem  Goals and Endpoints

    In  order to consider ecological impacts from  highway development, it is important to establish
 concrete operational goals for the maintenance of  ecosystem integrity.  Although the general goal of
 ecosystem protection is to protect or restore the diversity of natural organisms and natural ecosystem
processes, mere is no  one objective mat  will apply to all situations.  Because they may represent
important social choices, the establishment of goals and objectives must be undertaken with care.  For
Ecological Impacts of Highways                21                                    April 1994

-------
it til;
                •in"
                           six
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                                                                                        ' I
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                example, tiie federal and state highway agencies should involve not only the public, but other agencies
                g*™,,,^,_^,,.^__^__^u^ £or managing me affected natural resources.  This will help identify those
                instances where other parties have developed operational goals and  objectives relevant to  habitat
                Mi*!ftw.ii\iiivM|n::'	r:ori "	'"a""	•'	;!  "•	' '   ^ •" ••	* 	  •	"	:	 ..""•	"••	•••	
                '
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             ,1,	'i ;ilf
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                                                                                                        ..ii/'!, i .j.;";';*'!::;!	$	!:;"i.
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	,	1	^_r_i_i[|BirJ	"for the protection of ecosystems, and biodiversity," can be developed by applying
the relevant guiding principles outlined in this report  For example, measures to minimize landscape
fragmentation, or  to  preserve  old growth  forests,  can be  assumed  to  benefit  biodiversity without
quantifying the specific	biodiversity goal	to be 'achieved.  Highway agencies may have to limit their
biodiversity objectives to such general guidelines if more specific objectives cannot be identified.
IJIl'itL, '!ii).	i;	y'iHi,|i       ' •   ji-  itai^i^c i,i1:	:	A I .'"''' r ",tjs>!, IF  	is!i,-. wc'JKftFi .;	,,'B	iSmi ,'"•'$•,™ip*fc tii&.r'«	'	Mini . •	:.i."'i	 ',if'*    '
    Ultimately, ecosystem endpoints must be selected based on biodiversity conservation principles.
These endpbints should be quantifiable environmental attributes for which a baseline can be established .
and subsequent monitoring  done.   A wide variety  of objectives and measurement approaches are
potentially useful.  For example, Noss (1990) has delineated a hierarchical approach that incorporates
elements of ecosystem composition, structure, and functioning at four levels of organization: regional
landscape, communiry-ecosystem, population-species,  and genetic.  Incorporation of these individual
indicators, or endpoints, will depend on the ecological resources present, the impacts involved, and the
available hrfbrmation. 	      	       	    v	';	

r   The following table is an attempt to define categories of ecosystem endpoints that should be used hi
environmental assessments of highway development. One or more categories have been defined for each
of five general principles of ecosystem protection (derived from the original 11 principles).  Specific
endpoints for  each  category are described hi the next section.
               Table 2.      Ecosystem Endpoints  Associated with Ecosystem  Protection  Goals for  Use in
                "*	"'*"        Environmental Assessment of Highway Development
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Ecosystem Protection Goals
Focns on ecosystems. Address die needs of the
region.
Protect sensitive communities and ecosystems.
M ftTntani native diversity and natural processes.
V
Protect sensitive species.
Minimize fragmentation.
Ecosystem Endpoints
• Consistency with regional plans.
• Integrity of regional ecosystem.
• Area of sensitive communities.
• Status of sensitive communities.
• Native species diversity.
• Native structural habitat diversity.
• Status of hydrology, nutrient and energy
cycling, fire regime, and keystone species
interactions.
• Number of sensitive species.
• Status of sensitive species populations.
• Habitat connectivity.
• Habitat patch distribution.
• Number of contiguous habitat areas affected.
I I HI
               Ecological Impacts of Highways
                                                               22
                                                                                       April 1994


-------
5.2.1   Ecosystem Endpoints
        *    •
    The categories of ecosystem endpoints  defined in the table  may be thought of as "assessment
endpoints" in the terminology of Suter (1990),  and the more specific indicators discussed below as
"measurement endpoints." The designation of sensitive habitats or species is critical to endpoint selection.
In the context of impact assessment, the term "sensitive" applies to bom ecologically valuable species and
habitat, and to those vulnerable to impact.   Rarity is  often a good indicator of vulnerability, but the
following characteristics are also indicative of vulnerability:

    •   species requiring high survival rates rather man high reproduction rates may be more at risk
        (given that impact is on survival rather than on nesting or other reproductive parameters) (Mertz
        1971).

    •   species whose intrinsic rates of increase fluctuate greatly are most likely to go extinct, even with
        high average population sizes and high birth rates (Goodman 1987).

    •   communities with vulnerable keystone (sensu Paine 1969) predators or mutualists may be more
        vulnerable; similarly,  the presence of exotic species may dramatically increase the vulnerability
        of communities.                                                  •           . .   •

    As discussed previously, the selection of specific ecosystem endpoints, or indicators, is dependent on
the resources of concern and the data available.  In addition to Noss's  (1990) comprehensive list of
biodiversity indicator types, EPA's Environmental Monitoring and Assessment Program (EMAP) is
developing a wide range of specific indicators of environmental condition (Hunsaker and Carpenter 1990).
These indicators range from population abundances to  community indices (e.g., Karr's Index of Biotic
Integrity for fish communities) to landscape-level indicators such as the following:

        Abundance or density of key physical features and structural elements.         .
        Habitat proportion (cover types).                       .
        Patch size and perimeter-to-area ratio.
        Fractal dimension (amount of edge).
        Contagion or habitat patchiness.

    Research into ecological indicators is continuing and promises to provide a diverse toolbox of methods
for determining environmental change and identifying habitat impacts. As new indicators are developed,
they can be incorporated into  analyses focusing on the following categories of ecosystem endpoints:

Consistency with regional plans.

CEQ (1981) guidance  on the "forty  most asked questions" (46 Federal Register 18026) states that
environmental assessments must identify and evaluate conflicts with land use plans (all formally adopted
documents for land use planning, zoning and related regulatory requirements, even if proposed).

Placement of the highway corridor may conflict with  land uses assigned to specific areas hi regional
plans.  Each such instance should be identified and discussed in detail.
Ecological Impacts of Highways                23                                     April 1994

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  Integrity of Iregional ecosystem.                           •

  Once the boundary of the appropriate regional ecosystem is identified (e.g., the Greater Yellowstone area
  or the Chesapeake Bay Watershed) the impact'of the project on this ecosystem should be identified and
  discussed in at least qualitative terms.
                                 	 !'"'	•"' "'  '.	 ' ",„  '..	 	'	•	|	'  ' '  '  ....
  Area of sensitive communities.
 Distinct local ecosystems  and vegetative communities should be identified; where these h?hfrats are
 natural or ecological significant it should be	so indicated.	The	areal extent	of each community should
 be determined and  the absolute and relative decrease in area  (acres) calculated for highway land
 conversion impacts. As an example, sensitive habitats in the southeastern coastal plain include streams
 and rivers, riparian areas,  wetlands, bottomland hardwoods, scrub habitat, old-growth pine forest, and
 contiguous upland hardwood forest.  These and habitats of concern for other regions are described in
 Habitat Evaluation: Guidance for  the  Review of Environmental  Impact Assessment Documents
 (Southerland 1993).

 Status of sensitiv6_communities
                               ,  ;;	• ' •::;:,	':,,„: :;;„  "'.".  :,;	:;;  ,,	',	: ; ;.;;.•, ';,  ;;..". Ii;1.. ••;•..	:;; ,, '  .•;•..;. .;•,:.•;,::.
 In addition to determining areal impacts to distinct local ecosystems and vegetative communities, adverse
 effects to remaining habitat areas should be determined.  These include changes in the serai stage, loss
 of habitat features (e.g., caves,  cliffs, slopes, springs, and seeps), and decreased community vigor
 through, contaminant toxichy (e.g., needle loss in conifer stands caused by acid precipitation).
 Native species diversity.
                                                                         ijtiii:
                                                                                              	'*;,,!	i	us:
 Single species diversity indices have often been used ta justify the creation of additional edge habitat.
 However, these increases hi diversity simply reflect the replacement of local organisms with species
 adapted to disturbed or edge habitats. The invading species are usually common species  mat do not
 contribute to regional biodiversity. Measures of diversity should be limits to native species adapted to
 the intact natural habitat of the area.  Numerical indices that use multiple metrics (e.g., Karr's Index of
 Biotic Integrity) are often preferable to single metrics such as species richness.
       sttnetaral habitat diversity.

 Creation of modified roadside areas, stream channels, and wetlands usually results in the simplification
 of structural diversity, including the loss of critical microhabitats (e.g., snags and down material). These
 cnangess&bulffbeidentifiedart "quaiiitmledLThe UlS.Fish and Wildlife Service Habitat Evaluation
 Procedures (HEP) provides a method for describing habitat features important to wildlife (USDOI1980).

 Status of hydrology, nutrient and energy cycling, fire regime, and keystone species interactions.

 Highway development frequently alters surface and subsurface water flows.  Changes in rates and total
 volumes should be quantified and their effects on nutrient and energy cycling described.  Quantitative
 systems cycling studies may be possible hi some instances.  Disruption of natural fire regimes should be
 described.  Effects on ecological important species, such as top predators, major migratory populations,
Ecological Impacts of Highways
 1 liillfl !j> '"  Jill!1 «iiri „,, ",H!"  ;	I'1  """ii	.u'lit   , ,:!'  .n>
24
            »' ill  '" .•»!	!
              , I1 •   ' ,„,	»j
April 1994
                                       "	 Jli,::	; '-	>!!!v iLl'iilA,
                         ::"'	i::±	
                                                                              'i'!1"1"!,'  , ,„ '':''\\n:«'",

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 essential prey, populations, and dominant plant species, should be evaluation in terms of ecosystem
 impacts.'    "

 Number of sensitive species.

 Both rare and. ecologically important species should be identified and counted.  This include federal and
 state endangered and threatened species, species of special concern, migratory species, as well as keystone
 ecological species (i.e., those that control species composition of communities through strong predatory,
 competitive, or symbiotic relationships). The number of exotic species invading the area due to highway
 development should be included as a negative factor in the assessment

 Status of sensitive species populations.

 In addition to the number of different species, the demographic status of each sensitive species (including
 genetic  composition) should  be  evaluated.    Changes in  age  class  distribution,  sex  ratios,  and
 subpopuiation migration can be measured.

 Habitat connectivity.

 Fragmentation caused by highway development results hi reduced connectivity of habitats. Connectivity
 of single habitat types, or general classifications such as contiguous forest, can be measured using pattern
 analysis (e.g., fractal geometry) and GIS techniques.

 Habitat patch distribution.                                                   •
                                           N
 Another measure of me fragmentation of the landscape is habitat patch distribution. The composition of
 different habitat types and habitat sizes may be as important as connectivity for species movement and
 maintenance of metapopulations. Again using GIS techniques, quantitative measures of patch distribution
 can be obtained.

 Number of contiguous habitat areas affected.

 A simpler  method of measuring fragmentation is to calculate the number of contiguous habitat areas
 affected by highway development  Once habitat block sizes of interest (e.g., forest stands) are selected,
 the number and proportion affected can be determined.

 53     Gathering Ecosystem Information

   Successful application of an ecosystem approach to evaluating ecological impacts requires sufficient
 ecological information.  It is important mat information be collected on the distribution and status of the
 ecosystems or habitats that could be impacted by the proposed action to establish a baseline of existing
 conditions.  Assessment of potential impacts at the ecosystem level will aid in me protection of the
majority of  the  animals,  plants,   and microorganisms.   Information on species populations and
communities that are rare, sensitive, or otherwise in need of special protection (e.g., small, endemic
populations confined to localized areas) is essential as well.
Ecological Impacts of Highways                25                                   April 1994

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ill
!"(
      ! 1*1
      '
                                                ; ;!„.  I I'".1"!,1," .''  ,'! L! '  'IKS (j I, '' •  .'!, iff » | I , '•''':, ii; , J;'!."''  ,',''•  ' , i  « I'.'l


                    begin by assembling mformation from existing sources.  The recently mstituted
         Biological Survey (Larson 1993) should improve access to biodiversity mformation, assess
existing information, and improve and standardize information management.   Many federal and  state
agencies have already developed inventories of the distribution of biota and the ecological conditions hi
areas under men: jurisdiction.   The  following are several potentially useful sources of ecological
information.

   National Biological Survey (202-208-3733).
                           . Network (703-841-5300).
               Resource Agency Management Hans.
               Regional Land Use Plans (such as Coastal Zone Management Plans).
               Local Zoning and Growth Plans.
           Detailed discussions of the information available in the state Natural Heritage Programs, the Gap Analysis
           program of the U.S. Fish and Wfldlife Service, state biodiversity inventories, and the cooperative multi-
           state Fish and Wildlife Information Exchange are available in Incorporating Biodiversity Considerations
           Into Environmental Impact Analysis Under the National Environmental Policy Act (CEQ 1993).

           5.4     Analysis of Impacts

               Once the necessary background information has been obtained, the potential direct, indirect, and
           cumulative hnpacts of highway development on ecosystems ..... can be determined. This task requires the
         ' :: careful evaluation of the effects of the proposed action and each ...... alternative on attaining ecosystem goals
           and  objectives.    Ecological  analyses  should  consider  bom the factors  causing the destruction,
           fragmentation!, and degradation of habitats and the general principles for ecosystem protection. A wide
           range of techniques can be used to evaluate these ecological  hnpacts, including checklists, matrices,
           mathematical,models, and cartographic displays. No one technique is suitable for all situations, although
           geographical analysis  is of special importance  hi evaluating ecological  hnpacts..

              In addition to direct effects, CEQ guidance requires that indirect effects be considered:

               "EIS must identify all me indirect effects mat are known, and make a good fahh effort to explain the
              effects that are not known but are "reasonably foreseeable." (NEPA Section 1508.8(b)). The agency
              has tine responsibility to make an informed judgment, and to estimate future hnpacts on mat basis,
              especially if trends are ascertainable."             .

              Highway agencies seeking to consider ecological hnpacts hi men* project-level environmental analyses
           must address the same problems faced in other  cumulative impact analyses.  A basic problem is the
           disparity between administrative and ecological boundaries, that is, differences between the scope of the
           project decision and the scale of potential hnpacts in both time and space:  There are also difficulties hi
           „       ___.,,:_ etions on the same resource, and the additive or synergistic effects of multiple
           stresses. The use of an ecosystem approach can help address mis issue (see section 5.5).
                            ml
                            i in
           Ecological Impacts of Highways
                                                           26
                                                                                    April 1994

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5.4.1   Analytical Approach
        *    •                                                                   .

    As described in Habitat Evaluation: Guidance for the Review of Environmental Impact Assessment
Documents (Southerland 1993), die following considerations should be central to any process of ecological
impact evaluation:

    •   Apply an ecosystem-level perspective that considers the full  range of interactions among
        ecological components.                 -        .

    •   Assess the cumulative effects that arise from the additive and synergistic impacts of several
        degrading activities occurring over time or space.

    •   Analyze the true effectiveness of mitigation measures hi conserving natural habitats and their
        ecological values.

    Traditionally, environmental assessments  have  focused  on the following subject areas related to
ecological resources:

        Geological Resources       .
        Noise                                                             .
        Air Quality                                              .
        Water Quality                                 .
        Aquatic Environments
        Terrestrial Environments
        Endangered Species
        Wetlands
        Designated Natural Areas.                              '•   •

The consideration of aquatic and terrestrial environments has principally focused on economically or
recreationally important species of fish and wildlife,  in some cases, these  environments have been
subdivided into land use or vegetation based classes.  Rarely,  however, have the variety of natural
habitats hi project areas been accorded the attention given to wetlands or designated natural areas (e.g.,
parks, wild and scenic rivers,  and  recreation areas).  By  definition, an ecosystem approach to the
evaluation of ecological impacts from highway development will consider all habitats in terms of their
ecological importance, and therefore not exclude  important  environments that do  not nave  official
designations.  Similarly, this approach requires consideration of the full range of species of ecological
importance, not only listed endangered and threatened species.

    The Habitat Evaluation report (Southerland 1993) provides useful information on the status and trends
of habitats, and the- likely habitats of concern, in each region of the United States.  A review of mat
report and related material can facilitate, the identification  of sensitive habitats and .other ecological
resources.  Subsequently,  the functions and values  of the habitats and resources of concern should be
characterized by selected ecosystem endpoints  as discussed hi the previous sections. Lastly, the impacts
to these impacts are analyzed.  In summary, the following three basic steps can be used to incorporate
landscape-scale considerations into  both regional-level and site-level environmental assessments of
highway development-
Ecological Impacts of Highways -              27                                    April 1994

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V'Ptll1. ! ,lh  i' Mi
J'l Vfililllllllii'liii'i''.* i'
                                                                      I!,","ill'ii1"'1"1	Jit iEiiilB/ ' .'IIS-iii	i ""!•' i;!"",'ij'H',,,1',;"•,	-	; /''liSI'i1 •  ' . . ".ir
                                    HI    i ,  " ,i	:i   ill,,    .   .  'i, :  ' '',!,' ,	 ,  , 	,i,'t '"iiii	 ,' hi,, i; iiii juhi'",11 „:,	,"'	,,|i',,!,! ,,,!i,,,ri" i •*  "it,, ' ,;	' ,	'  ,|,	a1,!'1 pi1 nOii I'IIIIIP
                     'Si;1';,!	..'If'1"; '"} 'i'itjiili lil!"!!;  ll" 'i   '• "  , i'h  L. I1  '",   < „, , "" :!;i , I'1'1/, '! ,
T, "II ",1!	;"-"     ,!!!":-!	"f'Step i."'''  Classification and mapping of sensitive habitats.
f I iii,' i M' ' till   ,:  ini • f	T J V *', «* • • Iii  ii1! •* f, •• I l!" «';!#.;' i* ii < „ v« ,::' ;• i  '	i	i? ;„ ,!• "i;,,:!:	111	:* maa, wtte' ":< »\ IBIS;	.11 r  v it 1111 *	;'. •''; „ •' ' s	' ji'
*' *"'"' • '>!i l!":" "'"!  |l	! f	'!"t''-- ""*t''	'  characten^o"  of "habitats1 in terms "of" g^gg^-al ' yafu'e^ -^y fungous.
                    Step 3.     Comparative methods for quantifying different degrees of impact to these habitats.

                5.42   Classification and Mapping of Habitats

                    There are two principal systems for classifying natural resources: taxonomic ecosystem classification
                and regidnalization.  Taxonomic  classification systems  attempt to develop definitions for different
                ecosystem types, irrespective of their location (Pfister and Arno 1980).  This approach is similar to the
                traditional classification techniques of species taxonomy and uses a dichotomous key rather than a map.
                Regionalization of ecological resources is a map-based approach mat defines geographical areas of
                similarity based on 'ecbsys£eniisj orecosyslem^etennining factors.

                    Robert Baflej of me US. Forest Service and James Omernik of me EPA Environmental Research
                Laboratory m Corvallis, OR have developed comparable, but conceptually different, ecoregion maps of
                the conterminous United States. Bailey's (1980) map  is hierarchical, drawing on different factors for
                delineating regions at different levels (e.g., Divisions  versus Provinces).  His classifications  are
                principally "climate driven, "but"use; soils, landform, and vegetation at successive levels.  Omernik (1987)
                uses;      "          "      '     ' ----"--*-'-*     1~-"'     :   J      rj"cc   -*•——
including 'venation, hydrology, soils, etc. Omernik's maps have been refined in many states to provide
finer resolution for assessing water resource quality, while the U.S. Forest Service is incorporating local
scale ecoregions into Bailey's classification to facilitate forest management.
                   	;	'	:	.",	\	''•'•
    On the relatively fine scale of individual highway projects, vegetation is still the best indicator of
ecosystem type.  However, atonal areas (such a riparian zones) are still poorly represented hi vegetation-
based dassificatipnsJ ESchler's (1964) potential natural vegetation (PNV) units is the only organized
description	of major	above-ground terrestrial ecosystem diversity mat describes the entire United' States
in reasonable detail (Department of Agriculture, 1978), although NASA and cooperating agencies are
developing new vegetation maps from remote sensing data (Janetos, personal communication).  In terms
of ecosystem classifications, the new EMAP initiative at EPA is developing a classification of ecosystem
types for each of their major natural systems, including those for forests (developed by the Society of
Foresters)  and for deserts and grasslands (developed by the Society of Range Management). In addition,
statewide natural community classifications have now been completed  for each state Natural  Heritage
program (Larry Master,  The Nature Conservancy, personal communication).   There is now  good
agreement among state classifications on a regional basis, resulting in about 150 to 300 ecosystem types
per state.  More general vegetation types are in use by the natural resource agencies and range from
designations such as oak-hickory and spruce-fir associations to simple hardwood forest, conifer forest,
and rangeland	categories.
I!	ii( Li  ji:  t;:!"1!!'"; ,il!ji :,1!illi' ',„ jiliil i, .mil, i	I",i!i, ,;	ii	I •• J	ttf 'HI' , • I::;, 1 i!, M,"• KKf',1, ' , •• i	, ii	J-fj, «t,-1! ,W S raSfafflUH!1* i!' iST1'	i! iiWIIiil	f	v',	i;,:	 . •	.a sv \i  ,.  •,,/  , ,;„„	„	„
    Given lie advancement of mese efforts, and me many sophisticated habitat classification programs
at local levels, it is now reasonable to  expect a good delineation of habitat types and areas.for major
highway development projects.  Analysis of these data require graphic overlay capabilities mat are greatly
enhanced by the use of GIS.
                                m                                                          i

                Ecological Impacts of Highways                 28            .                          April 1994
'ii: «f ji • ..|.   :	i   /   iLiJir 'i •;	r,:11 ,  •.:   • .JIB ' i,  • , „ .iv:1,.	"'i11!1 ^ :iii< <  .     «f, •  • ,;„,  	•' • .»-„	 ''.,', ••, ••   ,i,ri •  ; ,•   v •ji!!,!,1 ,• r ,i ,,  •  ',.•T . ,.i,'  '	 " ,;!!|,, 0	' Jhii"111 i :J\VL , rw,, •
:!!|i  inl n •  .: " '''' ,;!"• :ii'• -• "„" ,' '!i'r.i  n'"!."'''!'!.!!!!1^ T*nt .|1|l!:i" '*<



,||i, ,|||f'ii ,i«'' | ,. V,  ,,,,,,: !i.   |  ', iu< : '  	i , "' ' '''' "'jfnn   ''fnjij ' , !l  „ " ' ", •'  ',, IN  't '	 !|  I' ,    , ,,. j.  , ,  ! I,' ...il"1 , ,, 'il ,,> ,,.'';,;   .  'ill.,..1.1 .'',," "'ill1,.!!' I I ',,',"• '  illl!'"!." 'ii ' ' , ;, ' |,.'•'„!„!! h.,',,,1 " ii |||j!;| ! .li,!fil.ii:


               • \	  ,    '  ' •	       :;    	•  	 ,'     "  .'.	    ,	I:'	;  ',	i".  	!	

-------
   GIS — Geographic Information Systems

      A  geographic information  system (GIS) is a collection of computer hardware, software, and
  geographic data that can capture, store, integrate, edit, retrieve, manipulate, analyze, synthesize and
  output all forms of geographically referenced information.  GIS approaches using remote sensing and
  existing data, such as U.S.  Geological Survey  quad sheets, are also being used in states to develop
  statewide land use maps for planning (Turner 1990).  Many more examples of GIS for planning are
  occurring on local scales as its power for determining spatial patterns is realized. GIS can be used to
  analyze the spatial relationships between species ranges and land use patterns, and to identify adequate
  buffer areas and potential habitat corridors for the maintenance of ecosystem integrity. For ecological
  evaluation, mapping of individual habitat areas is essential. Only through GIS or other graphical methods
  can the areas of habitat impacted and the changes in landscape patterns be quantified.

     Current GIS approaches to assessing the impacts of highway development use photographic imagery
  (usually low level aerial) to delineate vegetation using the Anderson Level I,  n,  or  m classifications
  In addition to accurate measures of habitat area, this imagery provides perimeteMo-area ratios and other
  measures of habitat fragmentation and isolation. Some analysts are hoping to  use the gap analysis
  program data developed by the U.S. Fish and Wildlife Service mat correlates Landsat Thematic Mapper
  vegetation imagery with ecosystem types and vertebrate distributions (Idaho Cooperative Fish and Wildlife
  Unit 1991).  Even more promising is me use of GIS  in highway planning that has grown since McHars
  (1969) advocated map overlay methods to determine me suitability of land for highway development
  The anticipated rapid growth of highway systems in North Carolina has prompted the State to create a
  Center for Geographic Information and Analysis to provide the locational  data  on  natural resources
  needed for effective highway planning (Fred Skaer, FHWA, personal communication).

 5.4.3  Characterization of Habitat Values and Impacts

    Once habitat areas have been classified  and mapped,  potentially  impacted areas  need to be
 characterized hi terms of ecosystem values and functions.  Traditionally, habitat characterization per se
 has been limited to wetlands. Others considerations have focused on individual species and water quality.

 Species Characterization

    In the ecosystem approach to ecological evaluation, analysis of impacts to individual species continues
 to play an important role.  To adequately consider the role of individual species in ecosystem protection,
 current analyses  conducted for endangered and threatened species and for species of economic and
 recreational important need only be extended to other rare and ecologically important species. In each
 case, predicted mortality from road kflls, contaminant toxichy, and habitat alteration should be evaluated,
.as well as indirect effects on population status, behavior, and movement patterns.

    The important factor hi species analysis is identification of the sensitive species.  The number of
federally and state listed threatened and endangered species is very small; however, many more species
can be included if consideration is expanded to include U.S. Fish and Wildlife candidate (category 2)
species and state species of concern. The best approach is to survey the species list of each major animal
group (e.g., invertebrates, amphibians, reptiles, birds,  and mammals) for rare species, species threatened
by other stresses, migratory species, and keystone species (such as raptors). Potentially sensitive plant
species can be identified through rare species lists  and plant community analyses mat identify dominant


Ecological Impacts of Highways                 29                                    April 1994

-------
l!.< liiK: i M'l'  :i: "":.
IK  jiiiii!!.	.	  UN	
II' llf, in?1" ' ""i,,  ,,'."l".'l'
 > litilLi"
till?'
'ill.1!1 'Mull,'I, I
  ii'',*' *»?' :,"«
   	"I I1 i;.'	il-
          Ililii
         » jiiii
                Hllll'lii ' T
                ilia:11 '"
                            	ii.  ;!'ii:l ';;•
                                                              "I "I	I'"" III	 "  111'," , . '! .. I'll
                                                               ii •?.;•.*, •  .ri;,:"-\.;	i
 '"pi'i: ii' :  . ' ':,»!' .I'll"'P11'1!"''  .'' -i ! ' is!' i I.
.'JrV*"!1' "i,",!1.' si/ "!:',,. ii	!; T'  '<•' "I "j
                vegetation layers, important food source plants, and species  critical to nutrient cycling.  Plants and    	
                jgnirrials associated with special or unique habitats (such as cedar glades, shale barrens, talus slopes, cliffs,  4fe
                and caves) should also be included.  Special	attention should	be given	to	symbiotic	species	such	as	 ^F
                butterflies and their host plants.

                   In the urban setting, fewer species will be present, but consideration should extend to the full range
               • of "urban" wildlife that increase as more edge is created around fragmented woodlots and wetlands (such '
                as raccoon, opossum, muskrat, squirrel, woodchuck, cottontail, chipmunk, meadow vole, American .load,
                robm ftf^ c3n"fliTi?iij flTiy deer).
                                            . III! Ill' .'''/"III ".'
               Aquatic Habitat Characterization
               '' jjjpl.	%^                  '
                IK IP. «».!•')*' Vtm "Oil. "L :•:;•! '• JC'^tlt It*:: "< •'!', '  m	ii •! ,1; i-l	It1'' »'	I'll.!;,!":' .',	!''	t	liiill" i'"'"11 ,	 iliilfl':'' '•.' • JS .*.;. "'vt (,!^ ,<'!",'•,...'' ..li!	fil-ik  :' i '	,. • IK**!;!1
                JII Traditional water quality analysis can be extended to mclude rigorous assessments of aquatic habitat.
               The FHWA Technical Advisory T6640.8A addresses'" unpacts to major	streams,	rivers; reservoirs, and"
               springs.'""' More specifically, the FHWA-reference manual for Assessing Water Quality impacts from
               Highway Maintenance Practices (Krame	et	all	1985)	prescribes a Habitat Evaluation Method which
               classified"jnnpactsT The habitat assessment has mree basic goals:
                                             'iin	iiililiii'iilii	,i,'V\,  TH
                                                                                                        1 Jil  ' "1111 ' 'I'!' "till1!1!*	FIE":  if
                   (1) Assess the resource value of the undisturbed habitat of the nearest receiving water
P                       downstream of the expected impact.
                           in 11   iiii i   i mi  i   ~        r
                |	IS ;,        ll ill	11  llli   •                   -                     •              |,
                   (2) Predict what effects' the expected disturbance might have on the habitat in terms of habitat
                       loss, alteration, or displacement.

                   (3) Assess the value of the disturbed habitat and determine if the difference hi resource
                       values constitutes a significant impact.
                Li( i  ,, :     MI   i ni ill  iii 11    i            ,                                    I
                ill1'	i>v;,	ill11!  liiiili!''  '  i    ni    .    i	        I'i   '  ' i   „  	   :'":'":	"«'.'»:	:.
               The method is based on the principles set forth in the Habitat Evaluation System (HES) as adapted by
               tie U.S. Army Corps of Engineers (COE, 1980) from the Fish and Wildlife Service Habitat Evaluation
               Procedure (HEP). The HES operates on mree basic assumptions: (1) the presence or absence, and
               abundance and diversity, of animal populations in a habitat or community is determined by basic biotic
               and abiotic factors	mat can be	quantified; (2) if the necessary habitat requirements for a species are
               present, 'then	a viable population will be, or	could be, supported by that habitat;	and	(3) general habitat	
               characteristics can be used to indicate the quality of a habitat and its ability to support fish and wildlife
               populations.
                                                                                                               v»5" I''ill! 'If'
                   The .HES method determines the quality of a habitat type using functional curves relating habitat
               quality to	quantitative biotic and' abiotic characteristics of the habitat	(i.e.,	a habitat quality index is	on	
               die ordinate ranging from 0-1 for every parameter;, a curve based on a particular measurement endpoint
               ••: iliiiiL'ijiii;;i|iiii:i.I	i	mm* u^S^ZZS 	               •*. *.	f	  >,   *  <		     	 —t	
               is used to quantify the effect).  Habitat size and quality are combined to assess project unpacts. The
                                    	'which is applied to'"each        "                         	
               Step 1. Determine habitat type or land use areas.
               Step 2. Derive habitat quality index (HQI) scores for each habitat type or land use category.
                       Score and^weight specific variables based on importance to habitat quality. Calculate an
                r;^; '•    aggregate score.
               Ecological Impacts of Highways
                                                                30
                       April 1994
         ''§11
                PIT' i  ' <;"

                ill!	I1' iiii!' .l,!'!!'-
                            ill-1  I;''"i
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                           },Mlif-,; tan	i

-------
 Step 3. The area of a given habitat type is multiplied by the aggregate HQI to obtain a Habitat
        Unit Value (HUV).  .

 Step 4. An HUV is projected for die impact of future maintenance activity based on estimated
        changes in habitat type due to such influences as channel dredging, sediment loading, and
        addition of toxic materials.

 Step 5. Calculate the impact: HUV after practice - HUV before practice = impact.

 Step 6. The significance of the impact on me resource value of the habitat is evaluated and
        possible mitigation requirements examined.

 This evaluation requires data from streams and lakes on .basic chemical, physical, and biological features
 of the  receiving water bodies.  Key variables required for streams include fish species association,
 sinuosity index (SI), total dissolved  solids, turbidity,  chemical  type, and benthic diversity (aquatic
 macroinvertebrates); additional .variables for lakes include spring flooding index, mean depth, shoreline
 development index, total fish standing crop, and sport fish standing crop.

    This approach to aquatic community characterization is similar to mat being used by EPA's.Office
 of Water to develop biological criteria hi support of the water quality standards program (EPA 1990).
 Biological criteria  research  has developed several  powerful  methods  for  characterizing aquatic
 communities (e.g.,  the Index of Biotic Integrity, see Karr 1991).  These methods are based on the
 presence, relative abundance, and condition of several species within an aquatic community and provide
 substantially better measures of habitat composition man traditional richness and evenness indices of
 diversity.  Although existing methods are most applicable to stream ecosystems, technical guidance is
 being developed for other waterbodies (e.g., lakes,  rivers,  estuaries,  and wetlands) (Southerland and
 Stribling, in press).  Application of new biocriteria methods, as well as modifications of HEP procedures
 (e.g., Pennsylvania's computer-based PAN HEP), should greatly increase the ability to characterize
 aquatic and other habitats.

    Qualitative methods  for  characterizing  aquatic habitats  include  assessing potential impacts  to
 waterbodies whose value have been recognized by official designations, such as Wfld and Scenic Rivers
 (as required by FHWA guidance). Unfortunately, too few rivers have been designated as wfld and scenic .
 to affect many projects. There are a much greater number of sensitive river segments in the National
 Rivers Inventory and even  more hi the American Rivers' Outstanding Rivers List (Southerland et al.
 1991).  Outstanding Resource Waters are also identified in state 305(b) waterbody assessment reports to
 EPA (U.S. EPA 1993).  A review of the rivers and streams included in these lists should be a mirnmuim
 requirement for characterizing aquatic habitats in the project area.

 Wetlands Characterization

    Wetlands have also generated substantial research into  methods for characterizing habitat.   The
Wetlands-FHWA Technical Advisory T6640.8A requires analysts to  identify all wetlands using the
 National Wetlands Inventory (NWI) maps, Soil  Conservation Service (SCS)  soil surveys, and field
 surveys, as needed,  to delineate wetland boundaries according to the current jurisdictional wetlands
manual (U.S. Army COE Environmental Laboratory 1987). Analysts may also designate certain wetlands
as exceptional resource value wetlands, including wetland special areas outside the highway corridor that


Ecological Impacts of Highways                31                                    April 1994

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I, ........ lii      '    '"1 ...... 11!      '        ,                      n ..... .......       1     i   1  '.       i ..............
                         •                                                           i


             may be subject to indirect and secondary impacts (West Virginia DOT 1992).  Impact factors include the
             size and proximity of the wetland, and the relationship of the wetland to its water source.
                                                  '
                 General wildlife diversity-productivity scores can be determined for specific wetlands using 10 criteria
             (Golet 1976, U.S. Army COE and Minnesota Environmental Quality Board 19S8). These criteria include
             3 based on vegetational community composition, 3 on wetland structure, 2 on wetland hydrology, 1 on
             adjacent land use, and 1 on water chemistry.  More commonly, the Wetland Evaluation Technique (WET)
             developed for FHWA can be done to determine a functional assessment (Adamus et al. 1987). Wetland
             functions of concern include nutrient removal/transformation, sediment/toxicant retention, sediment
             stabilization, floodflow* alteration, groundwater recharge,  production  export, aquatic diversity, and
      '; '*, ' ' " wetland-dependent bird habitat diversity.  WET n analysis .can be used to develop a rating value for
     "''rf, ': ;' wfldlife with a Mgh rating designating floodplaui wetlands, lai^e and vegetationaUy diverse wetlands, an^
             moderate-size wetlands that are oases or complexes with some interspersion (U.S. DOT and Michigan
     |!"  ill 'L;'1!1'1  , i» iiiiiiiHIIililUfc '"I'ii'iJiii'i'illiiilPliliinBHiSiiiliiiii!11 Jllllhi;!llllllllllllliiiiiii'i|l' j'liiiiiiiiiiiiiiiiiiiiiiiiau'ijiiiiUiiiiiiniiiiiiiPi,"1!!!, «niiii«iranii!Pi ..... iiiNiiiijiiiiiiiiiii'^iiiiiiiii^iiiiiPBr/iiiiiiJiniiiiJ!!:11'.!;' jiiii'ii irfiifc ..................... ............ ^ ..... ,n, ........ ,,, „» ......... , ..... ........................................... ™, .......... ,... yg ..... N™™,, [[[ ....... — ......  , ................. ...... , ................. s», . .......................................... .• .............
             DOT 1991).  Individual functions of wetlands such as plant and wildlife support, flood protection, and
             water quality should be determined and mitigation designed to replace lost values. FHWA has developed
             specific design criteria for replacing these functions  when creating wetlands (Marble 1990). Another
             approach is to apply TTEP to wetland characterizations. The use of HEP analyses is being reviewed for
             use hi wetland mitigation banking programs for highway development in North Carolina (McCrain 1992).

             Terrestrial Habitat Characterization                           .     .

                 Characterization of terrestrial habitats can follow the same models used for aquatic and wetlands
             habitats. In particular, the Habitat Evaluation Procedure (HEP) of the U.S. Fish and Wildlife Service
             and the Wildlife-Habitat Relationships  (WHR) of die U.S. Forest  Service .and certain state  wildlife
             agencies have been applied to multispecies terrestrial ..... communities (Schroeder 1986, O'Nefl et al. 1991, ........
             Short and Williamson 1986). As wife wetland and stream habitat evaluation methods, subjective values
             can be attributed to terrestrial environments. Following a Forest Service protocol, community importance
             values can be assigned based on 9 characteristics: diversity of plants and animals, density of plants within
             each community, canopy height, amount of each community in the state, number of game animals per
             community, geologic age and degree to  which the community is a relic, moisture requirements  of each
             community, ..... "the ...... relative degree ...... of insularity in the discontinuous phase witiiin climax communities of
             lower sensitivity", and degree of ecological succession. Each factor can men be weighted on a scale of
             2 to 10 and summed for the habitat type. (De (Waal Malefyt etal.1976).

                Where detailed characterization of terrestrial habitats  is not  possible,  qualitative methods of
             designating sensitive areas can be applied.  FHWA has existing guidance on the inventory of section
             4(f)/6(f) lands including state parks, national recreation areas, community parks, existing and. proposed
             National Wildlife  Refuges,  trails, and other  lands acquired or developed with Land and Water
             Conservation Fund assistance. These and other natural areas, such as local greenways, private preserves,
             aid ..... certain national forest, ...... should be identified and their 'pace ...... in the landscape described.  Other  areas
             that are more disturbed should also be considered  as they may be successfully functioning natural
             ecosystems of local importance. .Even these human-altered areas are becoming increasingly valuable (and
             vulnerable) as others like them are eliminated by urbanization.
                           ','"',. ..... ,   ~i: " " ............ "' . .......................................... •  ' ..... " .......................................... ".'„ ........................... I [[[
             !""!  Existing designations for identifying sensitive habitats can be taken from national forest management
             prescriptions (MP), e.g., wilderness (MP 5), areas emphasizing management for  species intolerant of
             disturbance (MP 6.1), and areas emphasizing semi-primitive non-motorized recreation hi a natural setting
                                                                                    i                      ;


-------
 (MP 6.2).  Otiier possible designations include special botanical areas (defined as state natural heritage
 program and  national forest management  plan  (MP  8) areas emphasizing preservation  of unique
 ecosystems),  areas  of national significance,  and research areas.    Many  other  federal and  state
 designations have been developed mat should be included in terrestrial habitat characterization. Many
 of these designations are compiled in the EPA report, Targeting Priority Natural Resources: A Review
 of National lists (Southerland et al.  1991).  Twenty-five lists are included comprising over 5,000
 terrestrial sites.  Many more state designated sites may be found  on lists mat are not yet centrally
 compiled.

    Landscape characterization from remotely sensed data is especially valuable in classifying vegetation
 as a means of selecting sensitive habitats.  The Anderson Level n Land Cover Mapping from USGS
 provides division of forest habitat in deciduous, evergreen, and mixed categories; additional data on local
 species associations can provide the more specific vegetation associations needed for habitat designations
 related to ecosystem protection goals.  For example, remote habitat may be given special consideration
 as h supports species intolerant of disturbance (e.g., bear, turkey, bobcat, fisher, warblers, woodpeckers,
 thrashes, gnatcatchers, and flycatchers). To evaluate forest fragmentation, the pattern of forests larger
 than 200 ac can be determined (because smaller areas do not support forest-interior species).

    Riparian areas are a habitat type of special interest because of then* inherent wildlife value and
 importance for landscape connectivity. The FHWA authority (Floodplains-FHPM  6-7-3-2 Location
 Hydraulic Study hi 23 CFR 650) "... to avoid or  minimize highway encroachments with the 100 year
 floodplain, where practicable, and to  avoid supporting land use development which is incompatible with
 floodplain values," can be used to protect riparian habitat mat provides ecosystem services whhin the
 floodplain. Areal measures of the regulatory floodway and 100-yr floodplain (high to moderate risk) and
 flood hazard areas (low to  moderate risk) are already incorporated into environmental assessments of
 highway development.   In a similar way, existing analyses of geomorphology, surface geology,
 groundwater, soil associations, and hydrology can be used to delineate ecological regions and then- unique
 watershed values.

    In a similar vein, other existing analyses conducted in  environmental assessments of highway
 development could be expanded to consider landscape  units as functioning ecological systems.   For
 example,  evaluation of impacts  to the aesthetic  and visual character of the site (using visual unit
 boundaries of 1/2 mi for 30 sec of visual  experience  at 55  mph) could be modified to encompass
 landscape ecology principles. In addition, air quality considerations focused on compliance with national
 ambient ah* quality standards (NAAQS) could be expanded to include vegetation effects not hi the
 standards.    •                                                       •

 5.4.4   Comparative Methods

    Ultimately the analysis  of ecological impacts from highway development must make a clear and
 concise comparison of the impacts of each alternative on each ecosystem endpoint. As pointed out hi
 Section 4, the suite of ecosystem endpoints  of greatest concern varies with the category of highway
 development, i.e., urban, suburban, rural, and wildland.  Similarly, the type and degree of impact may
vary with each category. In most cases, however, the methods for measuring the impacts are the same.
Ecological Impacts of Highways                 33                                    April 1994

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iJlii' |
   m\\
     The simplest method for comparing impacts is to develop a checklist for each ecosystem endpoint.
  This may be expanded  into  matrices that directly illustrate impact  degree  across  endpoints and
  alternatives. ......... Where ........ more complex relationships between impacts and endpoints' can 'be measured,
  modeling approaches may be used.  Finally, spatial measures of impact can best be compared using
  graphic methods. Inessence, the comparison of impacts is a table of alternatives vs. ecosystem endpomts
  that includes in each cell a qualitative or quantitative measure of predicted impact. Where possible, these
  cells  should summarize all potential direct, indirect, and cumulative impacts on the ecosystem endpoint
     To arrive. at such a summary table, individual analyses may be required for the impacting activities
  occurring during each of the four phases of highway development: planning design, construction, and
  operation.   Within each phase, the relative importance of die following stressor processes can be
 '
                                                                         n ..... , ...... f
         Alteration of topography. .............
        '^e^d^bn'xemoyd.

        '                         fl; ...............................
                                 gnd wqrming,
'li'iri'iiillllilli i ' IE!'" « IIIIKi'iii'i
f,r	inii'i'liL'.!!!!!, i  :,,!' i mi'liir:;:*
I" ™1|il'":1 ! ' n!!i!l|l>!"" *:"""
i'lij.Oln,"	 !„„:!	 ill'il	I1" •
ji1 """miiir,:, ' 'I'ir.ni ''timn'r I|M
                     tOXlCltV.
     •   Noise and visual disturbance.
     •  Dirett mortality from road kills.
   Hi , "!!" ji" '"i ........ Ill" iff,, ' iWllllil, mi • ,i|iil|i|||||ili|i ,F,, ..... J ..........................    ......
     Qualitative measures may be limited to a description of impacts to individual ecosystem endpomts.
 For comparison purposes, this requires summarization of the magnitude, duration, awl frequency of
>; impacts in an ordinal scale such	as high, moderate, or	low impact. Where possible, numerical measures
 o^r -mpact: gjjQ^j-j jje derived.  The simplest measure for sensitive habitats is area! extent.  The number
 of acres destroyed or degraded can be determined by overlays of corridor siting or construction design
 drawings with habitat maps.  More complex measures of impact are required to describe fragmentation
 and indirect effects.  Because of edge effects, forest habitat degradation may be more accurately described
 by perimeter-to-area ratios for individual forest blocks. Distance to adjacent habitat types can also be
 measured. Lastly, numerical measures of habitat mterspersion and connectivity can be given. Although
 there is no consensus or standardized protocol for quantifying edge effect, bom vegetation measures and
 animal behavior analyses can  be used to  define edge width.   Accurate evaluations of fragmentation
 impacts require an adequate means of'quantifying edge length and width (Yahner 1988).

     A simple comparative analysis was conducted by Bohm and Henry (1979) for highway development
 through a valued forest area surrounding Paris.  They set up  an  algorithm for  eliminating extreme
 alternative choices a j7rzon by usmg two conflicting criteria: the number of forest ac lost and the number
 of driving miles required.  They set bounds on the extreme amounts of forest loss per acre mat would
 be acceptable (e.g.,10 ac per mile and 100 ac per mile).  Where estimates of route impacts fell below
 or above these thresholds the route alternative would be eliminated. Although these ic™fc of comparisons
 can be constructed for any number of possible tradeoffs, the interactions among multiple scenarios rapidly
 increases the difficulty of the analysis.
                                                                         	i	
                                                                        	i	,
Ecological Impacts, of Highways
                                                           34
                                                                                     April 1994
         l"1"1,:,,,i»  : ''I Mill:  ..iJliliill " I . ' 	J1

-------
     Methods developed for the selection of transmission line routes can be adapted for highway corridor
  selection hi fee planning stage, and provide an illustration of possible ways of stanffordirigg differing
  impacts. De Waal Malefyt et al. (1976) attempted to quantify such important factors as number of unique
  vertebrates, number of endangered vertebrates, areal extent of each community in me state, degree of
  stress, and degree of negative impact from construction by measuring the total length of sensitive areas
  crossed by the transmission route.  These sensitive areas, included steep slopes, lakes, stream,  marshes
  and wetlands, forest, and specific areas of ecological sensitivity. They applied a screening process mat
  produced a regional sensitivity survey of the 23,000 m2 area and identified habitats of endangered fauna,
  geographically isolated biotic communities or those of limited extent, and research natural areas.  Two
  criteria were used to assign impact levels to areas with, the greatest sensitivities.  First, impacts to  biotic
  communities (based on floral composition) were described in acre-years per mile (as a measure of area
  and time needed to recover the natural composition).  Community impacts  were assigned levels 1 to 5
  and then were refined with 6 characteristics: areal extent, revegetation potential, floral density, support
  for vertebrates, and importance to protected species and stability.  The second criterion measured the
  geographic range of human-interest animals and identified critical habitat areas.  Impact levels of 1 to 5
  were assigned to each community based on potentially impacted area. The sum of these areas within each
  link of the transmission corridor  equaled total impact; the vector sum of all  links equaled the  route
  impact. This kind of acre-year analysis incorporates bom spatial and temporal impacts into a single unit
  analysis mat can be adapted to the evaluation of ecological impacts from highway development.

     While it is important to quantify impacts, care should be taken not to compare acreages lost among
 habitats of different values. la most cases, unique natural areas should be evaluated  separately with all
 ecological functions explicitly considered.

    The following table illustrates potential ecological effects mat might be identified for a hypothetical
 set of highway development alternatives.  In mis hypothetical example, a new highway project has  been
 proposed and two possible alignments are evaluated (along with the no action alternative). The project
 is planned for a rural area with substantial areas of bom agricultural and natural habitats.  The natural
 habitats are predominately upland forest (including old growth stands and wilderness areas) with a few
 wetlands.
Ecological Impacts of Highways                35                                    April 1994

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fc'llt'*!'"
i' vii'1'1'i n;i	iiiii!'.
i: 'tux i1"' i i':ii

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    "
fit'f '  •• -fii; 4.. •';;;<•:)	i;!!!:'  W
ti ';,i!ii   	i'iiwf  'i ,'"'  "	 "I: i ",:, ill: '  LI IK '  i  i » «,i • iiv- till


W ^'-i'illabiesr  S	gjpottSfcsii
t*1! • ::  iiiiJi Si'r'.iflUSi	irs:	i'  !	 	
;,  ;,:::;  *-'!  •;•:• •; ;.*•	,;;;••].:...*"'>j	|;f".	.;,;V*.Mji^"|'X'tw.w	!?* "  *? '&$*!!* f!!f.
IP! ,,':"'»,;;»•  , ,'" ,i :, i   • 1."'!'  • j1, !!- . • ,  ! ""• ill* •	», .irvi, 11  «• •'',', jjlk! .'«•	' li,'"'!',,''  *, •„  	,,!	 • "if1!! •+•' 'i,* t :!'•«! '  „ ,»!" I j'!"1'1 •   ' ,:'i  '"!!'''"' !'::i, i» i'i!''!! ii' Jiil!!,; i! ' !!!i!!';, •


Comparison  of Effects of Alternatives on Ecosystem Endpoints

                                                ,	i.	
::r%!l
 " ,,'	''Jiili
              ,
          ' iii1 T t ii1'1  '„,!» ii"
Hi,;, : "Illiijg? l;'i" ...... |; I 'i1'! i,,,,'i!i! Ii, ...... "iiFlii,,; ..... U1
    If. Hill1" ' ! 	 Jlllltnilr, 1|l	I " i
          , l1 111*  .....
Ii; ilKlllh • l i'1
in11 ir 'nil" !»" ,i<,. "i
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           nr in,  ii ...... ' .:„ ii


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          ; Jfli1!1
liiL.iiWiiiJIii11' 1 i..'lll|UI!; . Id	jl 1 ,,!!,i

"PfO^YS'I 'fc!M ENDPOINTS

Consistency with regional
plans*
Integrity of regional
ecosystem.
Area of sensitive

Status of sensitive

Wfifiv^ 
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 5.5     Evaluation of Cumulative Impacts

    The evaluation of cumulative impacts to ecosystems from highway development is an essential part
 of any environmental impact assessment.   Fortunately, the ecosystem approach to ecological impacts
 analyses recommended above incorporates the basic principles needed for evaluating cumulative impacts.
 Nonetheless, it is valuable to review the following crucial steps involved in cumulative effects analysis:

    1.  Defining the goals of me assessment.                                       . .
    2.  Setting the spatial and temporal boundaries of the study.
    3.  Establishing an environmental baseline for assessing impacts.
    4.  Selecting the impact fectors to be included in the study.
    5.  Identifying the role of impact thresholds in the study.
    6.  Analyzing the impacts of the activity (alternatives) relative to the baseline.
    7.  Recommending mitigation and monitoring based on the cumulative effects.

 These steps closely parallel the evaluation approach presented hi.mis report  Of greatest importance, is
 the need to set spatial and temporal boundaries based on the resource of concern, i.e., the ecosystem.
 In addition, the  enumeration of these steps highlight the additional information needed  to conduct
 cumulative effects analysis as part of the evaluation  of ecological impacts from highway development.
 Specifically, cumulative effects analysis requires an  environmental baseline against which to compare
 ecosystem condition (no. 3), identification of other related actions potentially affecting ecosystems (no.
 4), and thresholds of significant cumulative impact (no. 5).

    Cumulative impacts to ecosystems must be measured against a baseline condition. Depending on the
 timeframe of concern, mere may be a need for bom historical and future baselines derived from  trends
 hi ecosystem  change.  One of the special problems associated with highway  development  is the
 accumulated effect of individual components of the highway system and the secondary development mat
 often follows.  In assessing cumulative impacts  to  ecosystems, special emphasis should be given to
 including development activities mat reduce the  area! extent of .habitat types.  Lastly, thresholds of
 significant impact must be set. Because ecosystems are affected in some way by virtually all activities,
 the cumulative effects analysis problem can become  intractable unless significant levels of change are
 defined.

   A number of specific methods have been developed for cumulative effects  analysis.   Narrative
procedural guidance has been developed from reviews of existing methods (e.g., Horak et al. 1983, Lane
and Wallace 1988) and additional conceptual frameworks have been proposed by Westman (1985) and
Bedford and Preston (1988).  Mathematical representations of the cause and effect relationship have
included flow diagrams, networks, and matrices (e.g.,  Stall et al.  1987). More quantitative statistical and
modeling approaches based on analysis of historical patterns of impacts have also been developed (e.g.,
Gosselink et al. 1990).  One of the most useful approaches involves map overlay methods that range from
general landscape suitability, ratings (McHarg  1969)  to individual habitat patch preservation priorities
(Scott  et al.  1987).   The  recent  advancements m GIS technologies have greatly  increased the
sophistication of current map overlay approaches.

   The synoptic approach to cumulative impact assessment recently developed by EPA for wetlands
(Leibowitz et al. 1992) provides a practical framework mat could be adapted to any habitat type given
adequate data.  The approach rests on the selection of synoptic indices (actual functions and values within


Ecological Impacts of Highways                 37                                    April 1994

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                                                                                  I
                the particular environmental setting of interest) and landscape indicators (actual data used to represent the
                indices). By "associating a parameter of concern (such as integrity of interior forest songbird populations)
                with a measurable indicator (such as forest patch size), the cumulative impacts within the landscape can
                be determined.  These synoptic indices can men be compared across landscape subunhs (e.g., counties,
It ..... :' I, Mi  I (I  I |  ^1^^^^^^^^^^^^^      IIIIIIIIIIIHIIIIII I Illlllllllllllllll  111 I 1111 J ..................... *. [[[            r          .      ^    .      N "
tfwi in  iffl      watersheds, or ecoregions) to promote better decision-making and highway planning.
™n| "™" ~ |          '                "*        J'1|n|" : | " / '||f"' ^" ..... ~ ....... jj' , | ^ '|l|"°' n™" "                               |
                   For  many situations,  assessment of cumulative impacts on the regional scale,  so important  to
             *  understanding threats to ecosystems, poses major difficulties.  Frequently the region-specific data
            , ..... , , ...... necessary for such assessments are lacing, particularly within the time and "resource constraints often
                involved in ..... preparing environmental ...... analyses ..... (twin ...... and ....... Rodes ........ 1992). This emphasizes the need for
             :l ,. I ..... federal agencies to cooperate in developing regional baseline information. ........... Even ...... for small projects, it ......
             ;*f  should always be the objective of the environmental document to analyze impacts at the largest relevant
                  ale, based ...... on me ...... affected resources and expected impacts.      .....
                  1 ,t' ' ' : , ^ &' ' ...... sv ........ wiui ...... a .
                   '     '                  ^^     •   ' '1    •        '
. ..... >: ,,f | ....... „, ........ .  5 ..... !!|!i;il
                      ,
                'til,- an ' i ...... t s, f nil ...... ' . :: , jtii .
                                                .,      , ,   .
                                                • ..... .>, ,£ < ', : t" 'iii.*'1. ..... ..... IF..!: ...... •
                   FHWA recognizes me importance of regional analysis  and has taken a significant  step toward
                improving the consideration of cumulative impacts by publishing an 8-step framework for incorporating
                secondary and cumulative impacts considerations into the highway development process (FHWA 1992):

                   1.  Conduct area-wide planning  early  in the process and look  for  links  with .programmed
                       development and resource management plans.

                   2.  Where planning information is not available, use historical data and trends information as an
                       indicator of future Development .....          [[[
                   i   *   ill ii i    yn     .............................. l
11:111 !""llii!l" ......... "'
                   3.  Determine  recent  and expected  changes in development and resources  as a measure of
                       susceptibility of resources.
                                       *                                x                l
                   4.  Rdate information on trends m development to geographic scope of me project.
                                      * ......... • [[[ ' [[[ ; ......................  I .....................    .........   ....................
                   5.  Incorporate the time period defined by the project design life in the analysis of impacts.  .
                                                                              •'..!         '    •
                   6.  Assess the impact of all planned and potential development in areas influenced by the project over
                       its life.
                                                                                       !
                   7.  Estimate me contribution of the highway project to projected development based  on project
                                           or' facilitate devdqpmeat.  ''                              .
          .
     'i.Ti -I ..... Hli.
      .; ^
          . ..... '"" ;    8. ....... Develop ...... mitigations that are "reasonable and related to project impacts.  Recognize mat measures
        -I ..... Hli. .......... ...... I .............. ............ in".!!. ......... ............. ' ....... .................... iii ...... ill ...... i ..... €^ ......................... _ ........... S ......................... » ................. ., [[[ w .................... . ................ ,,,,,, ................................ £ ............. ~ . _   ,     -            ,     ..
           '    '       to address ...... future, development are often beyond the control of highway programs and require mat
                     '^^g^way ...... proponents work with local agencies to incorporate environmental protection provision

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  6. Mitigation Measures for Ecological Impacts of Highways

     CEQ guidance requires  that mitigation measures  be considered  even for impacts  mat are not
  themselves "significant" once the proposal as a whole is considered to have significant effects (46 Federal
  Register 18026, 1981). In me case of highway development impacts, these measures must include bom
  specific design alternatives (that could decrease pollution emissions, construction impacts, and aesthetic
  intrusion) and other mitigation activities such as relocation assistance and possible land use controls mat
  could be enacted.  To adequately consider ecological impacts of highway development, mitigation
  measures should be developed within the ecosystem framework and should consider the possible impacts
  of the mitigation itself.

  6.1     Ecosystem Approach to Mitigation

     Mitigation for ecosystem protection should address the cumulative impacts of all activities within the
  landscape (which, depending on the scale of the project, may vary from small  watersheds to areas
  exceeding several thousand acres) to ensure that ecosystem integrity and health are maintained.  The
  preservation of individual habitat areas is  important but not always  sufficient to maintai^ the ecological
  integrity of the greater ecosystem. In addition, the size, diversity, distribution, and connectivity of key
  habitat tracts must be conserved to provide for the natural diversity characteristic of the larger eco-
  complex or region.  The two most important methods for maintaining the integrity of fragmented habitats
  are (1) the provision of buffer areas,  and (2) the  creation of habitat corridors. Buffers represent the
  principal method of avoiding impacts to sensitive areas, and habitat corridors provide the best means of
  mitigating habitat isolation. The most common means of creating bom buffer areas and corridors is the
.  preservation of natural habitat along streams, steep slopes, and other sensitive areas.

    Habitat Buffers.   The preservation of a sensitive habitat includes bom the avoidance of direct
  conversion of the area and the maintenance of adequate buffer areas so mat  edge effects and other
 negative impacts do not affect the sites.  For example, highway corridors through forests  can  be
  "feathered" to avoid some edge effects (Gates  1991).  Additional areas adjacent to the corridor can be
 cut to create successions! bands of vegetation parallel to the corridor opening; mis reduces predation rates
 at the edge and minimizes the barrier effects.  However, a wider  edge results in less forest interior.
 Research into the impacts  on benthic  invertebrate communities indicates mat buffer strips between
 roadways and streams of at least 30 m are required to prevent alteration in invertebrate diversity and
 ecological structure (Erman et al. 1977).  These buffer strips serve to  mahitam the riparian canopy and
 to stabilize the stream  channel.

    Habitat  Corridors.  Mitigation of habitat fragmentation involves the maintenance or restoration of
 habitat "connectivity"   (Norse 1990).   One way  to address, the  fragmentation caused by highway
 construction is to reduce the effective width of a highway corridor and decrease the barrier effect. In
 addition to reducing the number of lanes or roadside area, providing wide, densely vegetated medians
 can facilitate movement of some species  across the highway.  However, road kills due to collisions
 remains problematic. For those species that cannot cross highways of any size, fragmentation must be
 addressed by the provision of habitat corridor underpasses. Corridors have been used successfully in
 wildlife management for SO years (Harris and Atkins 1990).  Corridors provide for the movement of
 armnaiSj serve as a population source, contain whole communities, and withstand natural disturbance
 events, but they also provide for contamination transmission (Csuti 1991). Unfortunately, because edge
 Ecological Impacts of Highways                39                                    April 1994

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  I III
                             III I   111
                                                                                                                ill   (IIp  II
                 effects reach 200 to 600 m into the forest (Pace 1990), optimal corridors widths cannot be achieved with
                 highway bridges and must be addressed when siting the highway.

                     Although the development of specific mitigation plans must be based on a thorough understanding of
                 tie site conditions, certain basic principles of ecological management should be followed when mitigation
                 measures are developed.   The following general mitigation principles apply to  ecosystem protection
                "efforts:                                                      '      .       '
41' il'Silll !'!  i fiM'iJll! ,
  1.   Base mitigation goals and objectives on a landscape-scale analysis mat considers the needs of the
 '

                I!:
"UK HI! ..... ,'t ;.iu 'IS,.!!!'
,11.1 'thin!'. ILIUM, '	 ihhlli :,,;
"I; ill'li1	, , i 111	Ki,,:,,!!1  ' 111  illilSil
iii; .MI,:,"!,! ; M, "i iin»:
  f], "!':,|, ' >•[	B
  iiillM :"!	 I	fill1 .,
      ,,
  2.   Mimic natural processes and promote native species.
 I  '!  :«, !•! "TBil1"., Foil1 '' "IIH'ilJ, ',;•,,*	• „„,,,•	, .»	   	  „, „	,,,,, ,, 	 ,, ,	  ,	,,	,„,,	„,„., 	,,	,	 ,

  3.   Protect rare and ecologically important species and communities.
 '	' Jl" :,;  'i:. 4TT  !j,i, nil JIN	I1: .til	^v " Tii 111 i1?: ,mx „ , :  .;, ,i «	UHI	> »„ 'i  ;,  r .1 j,/,,,.	 .IF!!,:™*!:':'!,!!!	::;»	HU'iiii'ir	iiii'rir	i'	I-IJHI ,1;,,	j'lki'	L,,',:„!  • „ ,> '1,1:,!. 'IT
 4.   Minimize fragmentation of habitat and promote connectivity of natural areas.
lk''"i O'tlf':1:'! "i"1 I ....... I" I1 ' Tllillli1" I"1 n I 1 1    II i ill        j
•;: ...... '  :=  ..                                                                  i,
 5.   Maintain structural diversity of habitats and, where appropriate, species diversity to promote the
      naturjl variety of the area.
                             III II   I nil I ill  II  Pill
 6.  Tailor management to site-specific environmental conditions and to the unique impacts of the
 !1'1:1 ..... :»'spcific degrading ..... activity.,                   '"' ............... ; ........    '
illiil:'::! ':< '(I'''1'-'!* '	"      7.  Monitor for ecological impacts and revise mitigation plans as	necessary.
.ir-HiUf.i i"1- " i,..     tin1 „ "'" .v"'V	'iiiiiitii (	t'liiiiiiii in  ii'f.	i;:"!	*37,	•	f-	;	•.	-,,.	,.,	 f?	5'		•. ,T	.:-	,*	.;„,	

        •         f>3,   	Mitigations for Each Phase of Highway Development

                    The first priority in developing mitigation plans for ecosystem degradation should be avoidance of
                 the impact.  This is usually a siring issue, i.e., locating all construction activities at a distance from the
                 habitats of concern.  The ecosystem is adequately preserved if all possible impact scenarios are accounted
                 for. Barring this solution, effective management measures must be implemented to ensure the protection
                ...of jhe habitats,,pf concern.  Failing effective management, mitigation falls to the restoration of habitat,
                 which is often problematic, or finally to compensation.
3; • iji I i' Li  if ,J : • •',	fit i \ ,'i1" ™{3v	r, {::Sirii-  :JJM • i;V ii"} \ if ii - "i'iiii ;n3," iiiiliii ii t;*~' f-'""!:: «•<" '** • •'':- >"",. iii,Hii" •;»','/9iitt. iwii>'	« •	»• I , '  ^,,  '/'  ,' l! '"i1*" ,>i*il>i 't



 IIIII   I           III            III                       II                                           ,
 IIIII    II         11 IIIII           I    •    . „. i
   III                 I               I     "i I  '                                   i II                HI       llll V

     *

                Ecological Impacts of Highways                  40                                      April 1994

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 6.2.1  Planning Phase
        *    *

    The planning phase involves all pre-design activities including die siting of the highway corridor.
 This is the most  important opportunity for mitigation of highway impacts because  it allows for
 consideration of the roll range of landscape-level factors.  The principal mitigation measure in the
 planning phase is avoidance of sensitive areas during the selection of the corridor route.  Because the
 route selection is only constrained by the purpose and  need of the project, alternative transportation
 options can also be considered in mis phase.

    As  soon as the purpose and need fox a project has been developed, environmental considerations and
 potential mitigations should be enter into the highway development process.  Incorporation of these
 concerns early in the planning process is the best way of avoiding irreconcilable conflicts. Consideration
 of alternative transportation options (such as railways and bikeways, or traffic management) should be
 viewed as initial  "mitigation" opportunities before the type of highway is selected. Whfle the range of
 alternative transportation options may be greater in the urban and suburban settings, these alternatives
 should  be considered for .all categories of highway projects. The planning phase is also the best place
 to consider effects such as reductions hi the carbon sink caused by vegetation removal and its implications
 for global warming.

    The next opportunity for mitigation is corridor selection. This is a critical step, especially in wfldland
 and rural settings, because it offers the greatest range of options for avoiding sensitive habitats. For large
 highway projects, corridor selection itself is worthy of an EIS, even though the actual roadway alignment
 will be selected at a later time.   In the case of Appalachian Corridor H (West "Virginia DOT 1992), a
 corridor selection process based bn a width of 2000 ft was used as a means of considering the many
 valued  natural  resources within the project area.  The only way to avoid habitat fragmentation and
 impacts to contiguous forest and remote habitat is to mitigate in the planning phase.  The vulnerability
 of many wildland habitats means mat even the most conscientious design and construction phases cannot
 mitigate adverse impacts from a nearby corridor.

    An important component in the consideration of corridor impacts is the likelihood and extent of future
 secondary development.   Again, these impacts can be especially devastating to wfldland habitats.  In
 devising planning phase mitigation for secondary development, the analyst should look at existing land
 use within potential corridors, and project possible future land use (forest, agricultural, and urban) based
 on current land use plans and controls. This requires consideration of state planning regions and local
 growth  centers. It is only in the planning phase mat conflict between ecosystem protection and economic
 development can be resolved. Traditionally, environmental assessments have been limited to identifying
 which alignment alternatives have the lowest potential for direct support of base floodplain development.
 This  approach  should be expanded to include development  on an sensitive lands, and  mitigation
 encouraged in the form:of appropriate applications of local zoning restrictions.

   The final opportunity for mitigation during planning is the selection of the highway alignment (usually
 a corridor of 150 to 300 ft). This is the step where specific sensitive habitats can be avoided to the extent
practicable given the general corridor route.  The mitigation goal is to avoid ecologically sensitive areas
 and limit encroachments to fringe takings rather than severances. To date, mis has included avoiding
 wetlands, large forested or vegetationally diverse tracts, raptor nests, and major wildlife travel corridors,
 as well as  minimizing construction parallel to streams  with  important fisheries.  As before, these
considerations should be extended to all sensitive habitats.  Mitigations for secondary development can


Ecological Impacts of Highways                41                                     April 1994

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•11 III  111  111 111
III (11  III I  Pill
                                                                             •:•: '.   : '.	I--"1
                                                                             ,„:;,„ ,•	L	
                                                                             ••iri • j1" - 	 	j |;
1(111111  II   111 111   III 111,, "ll'll1 Illi'!	 "Ml:i	."ill:' , 'lull	'!	'  I'll!!-',!!'/';, 
-------
Figure 1. Mitigations in the Planning Phase
Ecological Impacts of Highways
43
April 1994

-------
in, iiijijiyi!!1 'i"WIN"''.ill'1
it ;ji|iiiiiiij;p!:!««	' irt'i'iii.
      ,111, I  'viTlll,
                        Design Phase
                                                                                          i          •
                    The design phase involves the siting of the final right-of-way footprint and all aspects of structural
                design and within design mitigations. This phase also provides several important mitigation opportunities
                including both site-scale avoidance of sensitive habitats and structural modifications to the highway design
                that may reduce impacts  of fragmentation or off-site effects.  Design of corridor width, median type,
                roadside vegetation, and  location of borrow areas can all contribute to the minimization of ecological
                Impacts.  Specific structural  mitigations,  such as bridges, underpasses or tunnels, and fencing, have
                considerable potential for enhancing habitat conservation goals.
                	lill                                                        ||              , i,., ,'i  •	 ,,,111	'	,„»' 	'	,„

                    Once the highway project has been planned (both corridor and alignment  selected) many of the
                opportunities for avoiding sensitive habitats have been removed.  However, certain site-level changes in
                the roadway footprint can be made in the design phase and these changes can tnfaimfae effects which can
                not be avoided.  These include limiting impingement on adjacent habitats (through lane adjustments and
                bridge design),  minimizing barrier affects (through the use of bridges and water conveyance),  and
                reducing pollutionimpacts (through noise walls, curb design, and catchment basins). The unique problem
                of road kOls can be addressed through combinations of fencing and underpasses. At the same time, the
                Design phase provides the  opportunity for incorporating substantial restoration or habitat creation activities
                within the right-of-way (mitigation banking may be better considered under the planning phase).

                    Avoidance of sensitive habitats through highway design is progressively more important in suburban,
                rural, and wildland settings. Essentially, the strategy is to reduce the roadway "footprint."  Reliance on
                existing roadway alignments is a primary means of doing mis. It may also be accomplished by reducing
                the  roadbed elevation to  minimize shoulder width; by shifting the  alignment (e.g., to avoid pothole
                Wetlands); or by widening the median to encompass small communities or wetlands. A reduced footprint
                also allows for a	larger buffer zone between the roadway and sensitive habitats, especially stream and .
                        '	"""	""	
	I'"'11""""1'!';'!''1!!'

{! MB;" 'I	El! 'HIM  i 'i i :  aill'T lii	••	,	!r, ' i	I	mill r,	i	;	JUKMHIJ	, '"•' a	 ni
4:!    Even mough sensitive habitats may not be directly altered, nearby highway construction usually entails
   negative impacts associated with a "barrier effect."   Designs to ameliorate the effect of highway barriers
   should be based on an understanding of the functioning of habitat patches,  corridors, edges, and the
   landscape matrix in the project area (Gates  1991).  Mitigations for nearby wetlands include use of
   minimal practical slopes and median widths; maintenance of existing surface and subsurface hydrology;
   and provision of passageways through and around structures for movement of biota.  Burnett (1992)
  . recommends the following mitigation measures for barrier effects in forests:

      *   "Construct narrow roads.
.  . E;;:"*	Leave .the	canopy intact.                                         	•
 '    •  	Incorporate subrroad tunnels
      *'    Build long bridges (as opposed to culverts or tunnels) over gullies and waterways.

      Although the provision of underpasses for animal movement is still being researched, it can generally
   be said that long bridges are preferable (althpugji this entails higher costs).  Barrier effects have been
   demonstrated	for	reptiles	and	amphibians"	and some small mammals.   Certainly, the fall and spring
   migrations of amphibians are problems hi certain areas. In some cases, successful migrations can be
   facilitated with short-term traffic management, but roadway tunnels may be the preferred solution (Daly
   1993). Solid concrete median barriers pose an additional problem and ithas not been determined whether


   Ecological Impacts of Highways                 44                                      April 1994
                IIIHII i|h,  j,, "I111 Ml,!i;,!i ::, rniUl  ti'BIR  » ,	 , •  j, ;i,,,' ." , „ "|ii,J" ;|	f|  + • " '	„•	, iifll '„,, ";„,, ' ,,1. : ,„',,'	'„    Jl, .H1 "'•..•,,  >' <""'<   ' ••&>'! , ,,„, • • "• •;,  •; ,„ "| ' " :., " n
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        ijijiiiiiiiiiiiiiii,, AI	ill, i,,;. jiiiiiiigggijiiipi jiiiEyiiiiiPiiiingnii jiiiiiiiiEiaiini i iiiiMiiiiiiiiiiiiiiiiii;	iiiiiiiiiiiiiiiii, j. niiiii'i: iiiiiiiiijiiiiiiiiii^aiii,: „ iiijiniinii; iiiiiiiiiiiiiiiifi	HIE:: ,1111 < iiiiiiSiir: tii lii ijuii	IE jiiniii n iiiiiiiiiiiiiiiiiiiiiiiiiiiiii": JijiEaEiiiiiiiPiiiiihiiiiLiiiiiriiU':'.' ,iii! piiiniiiii!" ^ :i rj a :;<	IIPLJ nih JC'iiinijiiiBiiiiiii!'1 nii.'ii.iiiii'iiini,: jiii'viniiiiii'iiaiiiiiiiiiiiiibi pHiUiiiiiii'iinii:,; a i iiig'iiiiniiiiiiinuiiAf i	A, ? i^iinnini1: i! i<::ipi n iieiiiiiiiiiiiiiiaiiiiiiiiiiiiiiiiiiiiiiiiui .iiiiiiBiiiiii!',, •

-------
 passageways in these barriers would be beneficial for smaller species (Adams and Geis 1981).  Hunt et
 al. (1987) recommend using a variety of tunnel sizes, because new tunnels are predominately used by
 feral predators.  Many species also require regeneration of native vegetation around tunnel entrances
 before they will use them.

    The U.S.H. 53 project hi Washburn and Douglas Counties, Wisconsin is an innovative example of
 mitigation for ?™mai migration across a highway (U.S. DOT and Wisconsin DOT 1991). In mis project,
 the highway corridor passed through an important wolf migration pathway.  In order to minimi™* adverse
 impacts on  me wolf population, significant lengths of "wolf shift" zones  (areas with a wide, forested
 median)  were proposed.  Although mis wide median constitutes the minimal feasible barrier to wolf
 migration, passage would still be adversely affected. To mitigate for this impact, full control of access
 through mis section of the project (with no new private accesses allowed) was proposed. It was believed
 mat the benefit of precluding secondary development in me project area (thereby preserving this dispersal
 corridor) would exceed the adverse effects of the highway.  In addition, to ensure that wolves or other
 large animals such as deer or bear would not be restricted by the expressway, fencing would be installed
 only adjacent to farms wife domestic herd animals.

    Road kfll mortality is another important factor affecting a wide variety of species.  Fencing is a
 common solution, although the reduction in deaths must be weighed against increasing the barrier effect,
 especially for long stretches of  exclusive fencing (Leedy  1975).  Research into  the  use of box-type
 underpasses by mule  deer crossing under interstates with big game fencing (8 ft high) indicates that
 vehicle-deer collisions can be reduced by over 90% (Ward et al. 1980).  However, results indicate mat
 elk and pronghorn do not significantly use underpasses. All three species were twice as likely to avoid
 roads when people were walking nearby than when traffic was present. While fencing solutions may help
 resolve deer-human conflicts, Povilitis (1989) feels that road kfll problems are fundamentally a land use
 issue (because conflicts arise when deer occupy wooded areas finely interspersed over land) mat needs
 to be mitigated in the planning phase.

    Another impact from highway development mat can be mitigated with barrier design is noise and
 visual disturbance. FHWA  noise abatement criteria  (currently 67 dBA for  parks and 55 dBA for
 wilderness)  could be based  on  threshold levels of substantial  increase above ambient levels,  not
 predetermined levels.   Noise abatement measures (usually entailing substantially higher costs) include
 creating noise barriers of concrete,  stone, wood,  or earth; shifting the centerline away from sensitive
 receptors; and depressing the roadway below the level of sensitive receptors. Van Der Zande (1980) has
 shown that highway disturbance is especially severe hi open field habitats, and mat it cannot be eliminated
 by simply placing walls or trees along the roadside, since these features only partially reduce the
 disturbance. Where effects might be reduced by constructing me road below ground level, the benefits
 must be balanced against the tendency of this practice to worsen hydrological impacts.

   Perhaps  the most severe barrier effect mat can be remediated within the design phase is blockage of
 fish migration. As. stated earlier, the retention of natural habitat and maintenance of normal stream flow
 are best achieved by constructing bridges mat do  not impinge on the stream environment.  However,
 culverts are  considerably more economical; therefore it is important to set threshold conditions where it
 is appropriate  to use culverts in place of bridges.  Ideally, a culvert installation should not change the
 conditions mat existed prior to that installation, i.e., the cross-sectional area should not be restricted by
the culvert, the slope should not change, and the roughness coefficients should remain the same. Changes
 hi these parameters could alter velocity and sediment transportation capacity of the stream and adversely


Ecological Impacts of Highways                 45                                    April 1994

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               , mm .
                                                               • ; 3s ....... Jl •
* « ..... i'"' '«'
      .
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    ..' '! ...... f t- 'iiii "•! 'i
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    :l""i'ii
     |!:	ii!''!-;	iiiiki';1111   .a\ :>.K	i!:!'!	":'i>:i ;•	i>, «ia	n	«-:	
                      Stabilize cut and fill slopes,  shoulders, and median with perennial vegetation or non-erosive
            1 i:,' • ; IH'li:; ,'i, ...... irl • .911 ' t ..... j!M    ••'•i ......... li '.i ...... h i
                       materials such as riprap or geotextiles.
               of Highways
                                                              46
                                                                                                     April 1994

-------
    •   Omit the use of curbs for delineation and stonnwater runoff control where possible.  Consider
        leaving gaps in continuous curbs to allow transport of pollutants from the highway.

    •   Establish permanent discharge points for stonnwater, including directing stonnwater runoff over
        vegetated surfaces, using wet or dry detention basins, or using infiltration systems to retain
        runoff.                                                              .
Ecological Impacts of Highways                47                               .      April 1994

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 i     :i , i1!frt	•,,       ,1,'ln,; ; :       •  i  •;;     :  i, '<;i    A ,   t;.(  »«tf    im::;	u;1 KM • '.iifiiK «Mn; R»*J	:''  '
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            ;*.'; r Jtlli;  '(ii«f!«*Wi»iif,	" ii'lfi 'llitii!;:-,' JUT'- '•	' :iiii {If H !' - i" i' : S  • "ii'i'«f. "iff kill!1 <*'.','. ,"• '.if'S il


            	 ,„,,, n ,  ,	 , .j.nnf „,,,	 l|il| 	, ,,,, 	, ,  , 	 , 	, .I;,,	 HI	 „,,,,,	 	 	  , ,  „	
                      Hgure 2.  Mitigations in the Design Phase
                      I1
                      Ecological Impacts of Highways
i ',: w ':! ..... t: . a •: ..... t :;l!i  v kr/ ;»] ..... i ••• w- a^
48
..... ;;::!"
                     • ..... I ........... n • .- ...... i •;«": •
                                      April  1

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 6.2.3   Construction Phase

    The construction phase consists of the vegetation removal, earth leveling, and paving steps provided
 for in the planning and design phases. While each of mese steps is required by the preceding decisions,
 the specifics of the construction process can be modified to eliminate many of the short-term adverse
 impacts of completing these steps.  The opportunities for mitigation in mis phase are primarily pest
 management practices (BMPs) mat reduce sou* erosion, toxic runoff, noise, and other construction-related
 pollution.  Careful planning and supervision of construction operations can also reduce unnecessary
 vegetation removal and land scarring.

    Mitigations of construction impacts are similar in urban, suburban, rural, and wildland settings, but
 their importance may vary dramatically.  la wildland and rural settings, where mere are more sensitive
 receptors, minimization of pollution and disturbance impacts is especially important.  Even in urban and
 suburban settings, however, the cumulative effects of runoff from many highway projects may severely
 impact downstream waterbodies such as the Chesapeake Bay.

    The principal mitigation measure  hi the construction phase is strict application of  standard
 specifications for erosion and sediment control, including routine inspections (Krame et al. 1985). This
 involves the installation of erosion curtains, runoff settlement ponds, and stream diversions where
 necessary. In general, 200-ft grass filter strips should be provided around staging areas and special
 precautions should be taken to contain hazardous waste spills.  Where possible, consideration should be
 given to soundproofing individual sensitive receptors and or completely eliminating construction during
 critical nesting or breeding periods.

   An erosion control system plan should be carefully designed to minimally affect local water quality
 and to clean sediment-laden water resulting from the disturbed area.  If a stream passes through the
 construction area, it should be diverted or piped so mat it does not acquire sediment. All sediment-laden
 water is men channelized and directed to sediment ponds for treatment. Water should only be returned
 to the stream when it has a sediment load comparable ito the undisturbed stream. To accomplish mis, a
 ditch is  built above the project and lined  with plastic; a flexible pipe diverts the water; erosion bales are
used to  contain runoff; chemical agents may be used to settle clay silt.

   Construction can also install permanent pollution control measures marstabflize the disturbed area and
minimize soil movement through natural  means. This includes the planting of grasses and the placement
of rock  at culvert outlets and small streams intercepted by cut slopes. Revegetation should include early
topsoil placement, seeding, fertilization,  and mulching for all disturbed areas (including marsh disposal
areas).  Many new innovative mulches and nettings are available to eliminate erosion and minimize plant
growth delay. Retaining walls and sidehfll structures can be built of modular components to fit into the
natural topography and reduce construction time and limit impacts.  Bridges can use precast structures
and  on deck construction  techniques  to minimize terrain  disruption, tree removal, and stream
encroachment.  Haul bridges should be  used to eliminate crossing streams with heavy equipment and
specially designed machinery or mats should be used to  reduce soil compaction.

  . Stream relocation should consider the needs of the resident aquatic community.  Construction should
be limited to dates when spawning, nesting, and breeding are not at risk. If the relocation is permanent,
construction must be a true recreation and provide fish habitat in the form of deep pools, riffle areas, and
constant flow in new channel. The new stream should achieve a stable morphology and natural meander


Ecological Impacts of Highways                 49                                    April 1994

-------
i	^^^^^^^^^^^^       	!!	"!
                                                       ' ...........
                                                                 IT'^fT ..... !'" ...... f'f ..... P$n!''

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                   i,.* : a ........... •• ,
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                 pattern (Rosgen 1985), and use natural materials  and plantings.  The original gravel size should be
                 maintained in the streambed, and stream shading vegetation should remain on the banks.  Where habitat
                 structure have been lost, log dams,  channel deflectors, overhang bank cover, ranker structures, and
                 boulders can be added* Equally important is the maintenance of natural riparian zones by minimizing
                 Vegetation clearing and protecting areas mat are not cleared.
                                                                                          "'      :-'	,:	I	'	""""	"":"	=	
                     Many  innovative  methods are  available  for maintenance  of aesthetic characteristics following
              ' „;' construction.	A	return,	to	the	natural	landform	is	desirable for	ecological	as	well	as aesthetic	reasons	
                 (e.g., microclimate conditions). Careful landscape work concentrated near the base of fills and at the top
                 of cut  slopes can  blend the physical features  of the site.  Where slopes must be modified along the
                 roadbed, adjacent areas can be flattened and rolled to reflect existing landscape characteristics.  Rock cut
                 sculpturing can  retain natural fracture  lines and cleared areas can be  blended into  "natural" .forest
                 openings.  Careful revegetation efforts are critical and should use transplants of young trees from Hie
                 neighboring area,  as  well  as native grasses  and wfldflowers.    Monitoring should be conducted to
              ''  determine	if vegetative invasion from "natural areas is adequate.
                                              ik, ....... in ..... ai ........ iii ,
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                                                                                                -, i- si siij,' '1'i.ii	'"'t'l!	I'',
                                                                                                  	i	'	'•
                                                                                                i h,, ilM ,	| iii,| i	i  , i,^ |
                               t,iHi< "' •" IIIIIIIII i  ', "" i
  III ' III
                __ Vf>^ __ r ------- ,, — .,_
                  IIIIIIIII Iii,1',1"""!:!11';, ,| js,"", ....... TisIS,,- '":,'!:,' ..... 1  i:!:,


                                                                                                    i

-------
Figure 3.  Mitigations in the Construction Phase
Ecological Impacts of Highways
51
April 1994

-------
             6.2.4   Operation and Maintenance Phase
I in in
    The operation and maintenance phase is the long-term result of the three preceding phases.  A
 highway will necessarily carry traffic and require regular maintenance activities. A certain amount of
 '  jj^ig--"(jxjgi ^_g^runoff and atmospheric deposition of toxic materials) is associated with road
 traffic.  Street parotmg, cleaning, and periodic construction also contribute to these impacts. Mitigation
 opportunities in mis phase are basically long-term applications of BMPs similar to those used in the
 construction phase.   Stormwater retention ponds are one "of the most important.  Another, equally,
 important, mitigation opportunity is the requisite monitoring and enforcement activities required to ensure
 mat mitigations included in the design phase remain functional for the life of the project.
	  '	•	;	|	:	;	;
    As with the  construction phase, the pollution impacts of the operation and maintenance  phase
 generally have greater impact on the more sensitive wildland and rural habitats. However, because of
 the greater traffic volumes in urban and suburban settings, the cumulative effect of highway operation
 may be greater in these areas,  especially in receiving waters.   Fortunately, ft is likely that greater
 mitigative efforts through maintenance programs wfll be available in higher traffic areas.

   - General highway:managemlirtpoli^            can have a major beneficial effect on mitigating
 the impacts of highway operation and maintenance.  Even programs to reduce driving miles, automobile
 emissions, and roadside litter are important.  Direct mitigation measures in the operation and maintenance
 phase fall into  me following categories:
                                      	 •  	   	   	  I '   	  	!	
    •   Control litter and limit potential pollution sources.

    •   Properly manage the storage, handling, and application (at optimal rates wfth well-maintained
        spreading equipment) of deicing chemicals.
                            in i inn i     ii i i   ii   i ii  in   lit vw,,' i::iiii ™'' ii
                «   Manage pesticide and herbicide use so that sensitive receptors are not negatively impacted.

                •   Avoid direct discharge of highway runoff to receiving waters.

                •   Reduce runoff velocities through[flatter grades, drop sttuctures or baffles, br grassed waterways.


    si ..'I"-. ""  ' is'V	:	j^g™™jl^aj^	concentrations	m"	runoff by maintaining dense grass cover, increasing grass
                     height, and leaving cuttings on the ground,

                •   Properly manage roadside and median vegetation, using only native  species and enhancing
                     wildlife food and cover where appropriate (e.g., for bird species not subject to road mortality).

                Stormwater management  is an important  component of operation phase mitigation strategies and
             ^^^ ^g;^n™f ^^^                                             including vegetative
             controls, detection basins, and infiltration systems. Vegetation management is associated with stormwater
             management^  but also  plays  an important role hi the mitigation of wildlife impacts.  For example,
             vegetation can serve as noise buffers and shrub plantings can increase production of nesting birds (Leedy
             1975).  Mowing should be avoided prior to July so young birds and mammals can fledge and disperse;
             while, selective mowing and cutting can be used to maintain ecotone diversity. Invasion by exotic species
             Ecological Impacts of Highways           .52                                    April 1994
             I	

-------
 poses a special problem that should not be enhanced by plantings of non-native species along roadways.
 Driver education programs can be targeted at reducing the transportation of exotics and intentional road
 kills, especially of box turtles.
Ecological Impacts of Highways                53                                     April 1994

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Ill I     11111
                                       Manage Vegetation for
                                       _•__  _    ^Wildlife
                                       "and Control of Exotics
     Figure 4. Mitigations in the Operations and Maintenance Phase
     Ecological Impacts of Highways
54
April 1994

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  63     Ecological Restoration as Mitigation

     When impacts to ecosystems cannot be avoided or substantially minimized during the planning
  design, construction, and operation phases of highway development,  mitigation falls to  ecological
  restoration.  Recent experience with wetlands mitigation involving the restoration or creation of wetlands
  has unproved bom the science of restoration (Kusler and Kentula 1989, Marble 1990,. Hammer 1992) and
  the management of mitigation options for unavoidable losses (Kentula et al. 1993). Mitigation banking
  for highway impacts  to wetlands has been initiated hi several states under programs of varying design
  (Short 1988, Eoworth 1991). An alternative to banks are "joint projects" where a group of developers
  agrees to carry out  a specific mitigation project to  compensate for  specific losses.  Although the
 restoration of large  wetland  areas that  is possible under  banking  is desirable,  the difficulty .of
  compensating for  the loss of on-site and like-wetland-type values suggests caution in relying solely on
 mitigation banks  (Kusler  1992).   Nonetheless, substantial opportunities exist for integrating these
 innovative approaches into FHWA procedures dealing with NEPA and Section 404 requirements (FHWA
 et al.  1988).

    Adequate mitigation of ecological impacts from highway development may require restoration of
 habitat types  other than wetlands.  Fortunately, wetland restoration is  increasingly being seen as a
 landscape or watershed level activity (NRC 1992) mat includes restoration of other habitats (e.g., riparian
 areas  and forests).   At the  same time, new mitigation efforts are being focused on restoration of
 endangered species habitats (David Wyatt, Caltrans, personal communication). Although the difficulties
 in achieving sustainable restored wetlands wfll doubtlessly be duplicated as restoration is undertaken for
 other  habitat  types, considerable success has been achieved for many  habitats (notably forests and
 prairies).  The following five-point framework is  proposed for addressing ecosystem restoration
 (Southerland 1991):

    1.   Define the restoration goal.     .                 •     -
    2.   Specify the restoration objectives of sustainability and ecological values.
    3.   Apply a holistic approach to achieve  functional restoration.
    4.   Assess the restoration by comparison with reference  systems and integrated measures.
    5.   Use practical criteria mat reflect the desired ecosystem values for  each ecosystem type.

    Larger policy decisions, such as whether to restore for a particular use or for the natural condition,
 should be addressed in Step 1.  It is also the time to determine how to incorporate the landscape setting
 into the project goals. When the goal is ecological restoration, the objective of a "natural sustainable
 community" should be explicitly stated.  In addition, the specific suite of ecosystem values and services
 that are desired should be selected.  This wfll determine the degree of restoration required and the
 expected deviation of the restored system from the predisturbance condition. Even when it is impossible
 to return affected areas (e.g., medians and roadsides) to their natural condition, innovative restoration
 techniques can be used to better integrate the areas into the surrounding landscape (Barker et al.  1993).
 Even simple tree planting along highways by  organizations such as American Treeways and Maryland's
 Cloverleaf Foundation (in coordination with state highway departments) can benefit the landscape
 (Rodbell 1993).

    The actual restoration steps required will depend on the condition of the degraded habitat to be
restored.  Two classes of restoration can be envisioned for highway-related impacts: (1) restoration of
habitat which remains intact but is degraded by highway development activities and (2) restoration and


Ecological Impacts of Highways                55                                    April 1994

-------
iin ii	mil	i  "lit
ii]	WiiilFJlihiJi':,,::!!,!!!1'!" 	mill1 IF	•


 Jlllllllllll	|||l|< liiiiNj'Ji'llfr'f,,,!!1!1!1!!1,:1' 9,H'
creation of habitat (both in-kind and different habitats) as a replacement for habitat mat has been
converted to "highway pavement or other incompatible use. The second class includes restoration or
creation within the highway corridor of habitats that provide desired landscape functions but were not
specifically degraded by highway activities.  It is FHWA policy to encourage states to convert excess
rights-of-way to public uses or to joimvuse projects (Linker 1989). Increasingly, joint-use projects are
being undertaken to construct engineered wetlands for basinwide control of nonpoint source pollution and
water qpjjty improvement. Other types of restoration within extensive right-of-way areas include habitat
enhancement for certain birds species or restoration of remnant of prairie plant communities (Drake and
Kirchner 1987).  The most important factor in conducting right-of-way restorations (and maintenance)
is the control  of exotic species.. Bom accidental and purposeful introductions of non-native species
(especially plants) must be avoided.

   Depending on the seventy of the degradation, ecological restoration will intervene at one of. the
Slowing stages of restoration: detoxification, creation of physical structure, restoration of chemical
balance and nutrient supply, return of vegetation and soil microfauna,  integration of habitat features and
spatial heterogeneity of patches, and colonization with fauna.   Whatever the method employed, the
assessment and modification of the restoration effort should be based on comparisons with appropriate
reference systems to ensure that the desired ecosystem structures, functions, and values are attained. This
reference-based approach may be most useful when combined wim a regional ecological classification
fsuch as Omernik's (1987) EPA ecpregions concept) and integrated measures of ecological integrity
_,_s^_..^_,	,._g___g	_™_m_	£—j.^	— iggjj'g (199 j) index of Biological Integrity).
6.4    Mitigation Monitoring

""'' ^Monitoring is essential to understanding the effects' of	a project.	It 'is	likewise critical to evaluating
Jne. Degree of implementationand successor failure of mitigation efforts.  Effects observed through
Monitoring can help modify project management or improve future decisionmalting on projects with
similar impacts, or in similar areas (Canter 1993). It is unlikely mat  adequate information on project
effects and mitigation implementation and success will be  obtained unless it is provided for in the
monitoring program.

    Many of the elements necessary for adequate monitoring will have been developed as part of project
planning and environmental analysis.  These include the following (Noss 1990):
                      Gathering data.
                      Establishing baseline conditions.
                      Identifying ecological elements at risk.
                      Selecting ecological goals and objectives.
                      Predicting likely project impacts.
                      Establishing theobjectives of mitigation.

               The following additional monitoring-specific steps can build upon these elements:

                  •   Formulate specific questions to be answered by monitoring.
                  •   .Select indicators.
                  •   Identify control areas/treatments.
                  •   Design and implement monitoring.
               Ecological Impacts of Highways
                                              56
April1994
                                              i Jii:M^

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    •  Confirm relationships between indicators and goals and objectives.
    •  'Analyze trends and recommend changes to management.

    The breadth and specificity of the monitoring program will be determined by the habitat mitigation
goals.  Mitigation of habitat impacts in the planning and design phases usually involve avoidance of
sensitive  habitats  and  monitoring is required ensure mat the distribution of habitats was accurately
understood and that the attenuation of impacts at the habitat boundary were as expected.   Mitigation in
the construction and operation phases primarily involve control of pollution.  This is especially true for
wetland and aquatic systems where, after physical alteration, off-site impacts to hydrology and water
quality pose the greatest tfrre**   Monitoring of pollution control  measures is an essential .part of the
mitigation of highway  construction and operation impacts.

    The fact mat many restoration projects designated as mitigation have not achieved their desired
objectives is well  documented.  It is also  believed mat mitigation measures for many projects are  not
adequately implemented or enforced.  Therefore, determination of the true effectiveness of mitigation
should be the goal of monitoring programs.

    In the case of mitigation based on ecological  restoration, monitoring is essential  to determine
restoration effectiveness, and thus mitigation success. Practical criteria must be selected for use in
evaluating the success of restoring the habitats of concern.  Because the  constraints of  practical
measurement are already being considered by various agencies in the development of environmental
monitoring programs,  a greater range of validated  quantitative ecosystem parameters may  soon be
available  for evaluation of restoration success (e.g., Hunsaker and  Carpenter 1990).  The following
categories of criteria are proposed as the minimum from which habitat restoration indicators should be
selected:

       Areal extent
       Absence of contamination     .
       Hydrology
       Water chemistry and quality
       Physical structure and soils
       Nutrients
       Productivity
       Microbial community       -                                    .             '
       Vegetation
       Habitat structure
       Biota
       Biological integrity
       Population response.
Ecological Impacts of Highways                57                               .    April 1994

-------
ill  1,1    I,   II	
                                 HI,	in	,i	i	•
......... I/
>' ..... Hi "i
                                             it,1   .......... '
                                                                                11 Hi
                                J'!"'!1 Til'!!"!,,:'.  ' 'Hill'D1   i1 Till:
                                                                                 i,1 j'«  IK,,,.   I1,:  'I ..ill"
                     • III
                     III!"111
,M 1 hjiuli,  /''"i* 1,1.11   ' .' II1'1    fi'J!',:   if  "I"!i,   ,"''"i I"1,!  it'lill!,!!11!1   111,,,,! III
                                                                                           ,;< Hi.,, ;, jiiii •": i	:f\[ :"!>•'    '  ,:  I|;;;;i;.,!i'iii i,'1"1,;,  'SNiim	  .iJi'i'nihi'.T	u1,1"1
                                                                                                                                                              	1,  	 P'll"1 ,'! 'Li11., ,', ,i:   'illl',,,*  V1"!:!'.1'I, "I '"11* ''.JIlHIIIIIili!! 'fl'S'iii'ii1'',1,'!'	!	Ullllllll
                    Ecological In^acts  of Higjiways
58
                                         April 1994
                                                                                                                         Sv'M^Mlii.'-'^'rr.lii	^:>^"''f^:V  'l-'.^/"!1:^!
                                                                                                            '!' "i^iiHKii'J 'gR'ininiH 'HifeiiiJ1 .lii;1""!]!!!'!! V/: rJIIBII/ii'iiHaj* vli!1iliiillii|liiii!i||lLiii'Ullii:|Mi;i"1lii1i;lfl	IM" ;	!!(," ll,i; :l !i;s!i, ii!,,/1  ; '  "<:;' 1,1; SL illOrlV Jliifi1

-------
 7. Summary of Mitigations for Ecological Impacts
    The following table is a summary of the principal mitigation measures recommended for highway
 impacts arising in each phase of project development (planning, design, construction, and operation)
 within each of the four environmental settings (urban, suburban, rural, and wildland).

 Table 4.      Principal Mitigation Measures for Ecological Impacts By Phase  and Setting of
              Highway Development

Planning

Design
Construction
Operation
Urban
Use' alternative
transportation
options
Fence roadway
to reduce road
kills
Reduce erosion
and pollution
effects through
best management
practices
Conduct trash
removal and
ensure operation
of stormwater
controls
Suburban
Use alternative
transportation
options and select
alignment to
avoid sensitive
environments
Fence roadway
to reduce road
kills and provide
CQTHieCtivfoy of
habitat with
bridges and
underpasses
Reduce erosion
and pollution
effects through
best management
practices
Ensure operation
of design
mitigations ^^i
stormwater
controls
Rural
Select corridor
and alignment to
avoid sensitive
habitats
Provide
gOHHfl^jv|ty of
l*«»V!*«t* «v«£*V
naoitat witn
bridges and
underpasses
Apply best
management
practices and
protect sensitive
receptors' with
walls and
nonintrusive
construction
schedule
Ensure operation
of design
mitigations and
stormwater
controls and
manage roadside
for rare
communities

Wildland
Select corridor
to avoid
sensitive habitats
and control
secondary
development
Reduce roadway
footprint and
provide.
connectivity of
naoitat witn
bridges and
underpasses
Apply best
1713713 P&TTl&flf
practices and
protect sensitive
receptors with
walls and
nonintrusive
construction
schedule
Ensure operation
of design
mitigations and
stormwater
controls and
manage to
control invasion
of exotics
Ecological Impacts of Highways
59
April 1994

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iHllhl
1 ....... 1,1
| ...... IK
       ............... (in
Ecological Impacts of Highways
     60
April 1994

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 Adamus, PJR., EJ. Clairain, Jr., RJD. Smith, and R.E. Young. 1987. Wetland Evaluation Technique
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 Bausch, C. 1991. NEPA Integration: Effective, Efficient  Environmental Compliance in the 1990s.
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 Bell, M.C.  1991. Fisheries Handbook of Engineering Requirements and Biological Criteria. U.S. Army
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Bohm, P. and C. Henry. 1979. Cost-Benefit Analysis and Environmental Effects. AMBIO 8(1): 18-24.

Buechner, M. 1987. Conservation in Insular Parks: Simulation Models of Factors Affecting the
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Burnett, S JE. 1992. Effects of a Rainforest Road on Movements of Small Mammals: Mechanisms and
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              •ill ill      i   Hull II   lllllll lii         I            I          nP III j ill    i i| i       II   IN  i  II   n|i      i l	Ill I  ill
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-------
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I'll11 111	  in  i   ilium	'I	iiiiiii  	iii,11'{	i  	i         i <    i i	        iiiiii     ,1 i  i  11	in111   i	  n hi	Hi  ill   i,' ti
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                           iii  iii'iii              i                      i         i ii in   n  i  i

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 Leibowhz, S.G., B. Abburzzese, P. Adamus, L. Hughes, and J. Irish. 1992. A Synoptic Approach to
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Ecological Impacts of Highways                69                                   April 1994

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             SECTION 5.2

   EXAMPLE 2: ENVIRONMENTAL IMPACT
ASSESSMENT GUIDELINES FOR MINING (ORE
             AND COAL)

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         EIA Guidelines for Mining
Environmental Impact Assessment Guidelines
      for New Source NPDES Permits
         ORE Mining and Dressing

                   and

     Coal Mining and Preparation Plants
         Point Source Categories
             September 1994
   U.S. Environmental Protection Agency
         Office of Federal Activities
           401 M Street, S.W.
         Washington, D.C. 20460
                                        ; 'Printed on Recycled Paper

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                      DISCLAIMER
This document was prepared for the U.S. Environmental
Protection Agency by Science Applications International
Corporation in partial fulfillment of EPA Contract No.  68-W2-
0026, Work Assignment 27-1.  The mention of company or
product names is not to be considered an endorsement by the
U.S. Government or by the Environmental Protection Agency.

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 EIA Guidelines for Mining	        ^     	Table of Contents


                               TABLE OF CONTENTS
 1.  INTRODUCTION  .	  1-1

     1.1  PURPOSE OF ENVIRONMENTAL IMPACT ASSESSMENT GUIDELINES . . .'	  1-2
     1.2  SCOPE OF THE MINING INDUSTRY	  1-3
     1.3  ORGANIZATION OF GUIDELINES	 :	1-4

 2.  NEPA REQUIREMENTS AND PROVISIONS	i	,	 2-1

     2.1  OVERVIEW	f		2-1
         2.1.1  EPA REQUIREMENTS FOR ENVIRONMENTAL REVIEW UNDER NEPA	 2-2
         2.1.2  ENVIRONMENTAL REVIEW PROCESS FOR NEW SOURCE NPDES PERMITS  	2-4
     2.2  TRIGGERS FOR NEPA REVIEW ACTIVITIES . . ..	2-7
         2.2.1  PRIMARY CONDITIONS THAT TRIGGER NEPA REVIEW	'.'. 2-7
               2.2.1.1  New Source Determination	1 ... 2-7
               2.2.1.2  EPA is the. Permitting Authority . . -	2-7
         2.2.2  WHEN is AN EIS REQUIRED?		2-8
               2.2.2.1  Impacts to Already^degraded Environments and Cumulative Impacts ....... 2-9
               2.2.2.2  Uncertain Impacts	  2-11
               2.2.2.3  Delayed Impacts	 . ;	  2-12
               2.2.2.4  Duration of Impacts  	  2-13
               2.2.2.5 Transfer of Responsibility for Facility	  2-13
               2.2.2.6 Controversial Actions and Impacts	  2-13
         2.2.3  THE RELATIONSHIP BETWEEN NEPA REVIEW AND NPDES PERMITTING AcnvrnEs .  -2-14
    213  LEVELS OF REVIEW	,	  2-15
         2.3.1-  ENVIRONMENTAL INFORMATION DOCUMENT (EID)	  2-15
         2.3.2  ENVIRONMENTAL ASSESSMENT DOCUMENTS (EA) -	'.	  2-15
         2.3.3 . ENVIRONMENTAL IMPACT STATEMENTS (EISs)	  2-15
    2.4  INFORMATION REQUIRED FROM PERMIT APPLICANTS	  2-17
    2.5  TIME INVOLVED IN PREPARING AND PROCESSING NEPA DOCUMENTS  	  2-17
    2.6  LIMITATIONS ON PERMIT APPLICANT ACTIONS DURING THE REVIEW PROCESS .  2-17

3. OVERVIEW OF MINING AND BENEFICIATION  . . . 1 .		.3-1

    3.1  ORE MINING	3.!
         3.1.1  EXPLORATION	3-2
         3.1.2  SITE DEVELOPMENT	  3-3
               3.1.2.1  Construction of Access Roads, Rail Lines, or Ship/Barge Terminals	• 3.3
               3.1.2.2  Construction of Mining Facilities	: . .  3-3
               3.1.2.3  Construction of Mill Facilities		3-4
               3.1.2.4  Other Pre-Mining Activities	3-4
         3.1.3  MINING	3.4
              '3.1.3.1  Surface Mining	3.5 "
               3.1.3.2  Open Pit Mining	  3-5
               3.1.3.3  Dredging	3.5
               3.1.3.4  Underground Mining	3-6
               3.1.3.5  In Situ Solution .Mining	:	  3-g
         3.1.4  MINING WASTES AND WASTE MANAGEMENT	;..  3-9
               3.1.4.1  Mine Water	3-9
               3.1.4.2  Waste Rock	  3-10
                                                                         September 1994

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Table of Contents'	•	       EIA Guidelines for Mining
         3.1.5  RESTORATION AND RECLAMATION ............"'.... I                3-11
   ' 3.2   ORE DRESSING (BENEFICIATION)  . .	'. . ',	  3-13
         3.24  GRAVITY CONCENTRATION	,	\. .  3.13
               3.2.1.1 Sizing	. . .. . . .... . . . . . . . . . . . ._\ ,. . f ,^ . r . .  3_14
               3.2.1.2 Coarse Concentration	n	  3-15
       1        3.2.1.3 Fine Concentration  . . .	 .  s-ig
               3.2.1.4 Sink/Float Separation	 . .'".'	 . . \ . ". .  S-ig
         3-2-2	^ASKSKSSABffiff.	».	el«	-•	™.i'r	f.	, •"• • •• •	._.'...	,_,..*,.,.,	i...,:	,-,	5-18
         3.2.3  ELECTROSTATIC- SEPARATION	•-	  3-19
         3.2.4  FLOTATION.	  3-19
         3.2.5  LEACHING .:...... 1.......,".'.	  3-20
         3.2.6  BENEHCfATION WASTES AND WASTE MANAGEMENT	  3-22
               3.2.6.1 Mine Backfilling  ...... ."".	.".'"	1.".	.'	'.	IT	.'.".	.".".	.".	.".'. .  . •;  3-23
               3.2.6.2 Subaqueous Disposal	 .	  3-24
               3.2.6.3 Tailings Impoundments	'	  3-24
               3.2,6-4 Dry Tailings Disposal . ."	  3-28
   3.3  COMMpprr^^PECIFIC MINING AND BENEHCIATKW PROCESSES	 .  3-29
        3.371	GOLD ANb~Sn.vBt.."'	..:......".".'."."... :".'.....'..	  3-29
               3.3.1.1  Geology of Gold Ores	       3.39
               3.3.1.2  Mining	;	  3-34
  	i	..•..	'-••.-	313.1.3  Beneficiation	•	'	  3.37
       3.3^   GOLD PLACER MINING	  3.55
               3.3.2.1  Mining	;	  3-58
               3.3.2.2	Beneficjation	._..._._.	..._..	 .._.... ._....	 ._.	._. ... ,	.,.„,,„,	 ,,„,. . .  3-59
               3.3.2.3  Wastes and Management Practices . . . .'	3-60
  	3.3.2,4;  Environmental Effects	.•	'  3^2
     - 3.3.3   LEAD-ZINC  ".'*		..........   3-63
              3.3.3.1	Mining	.".	.'. .'. ". .T.'. . .'. .'.'".'.".'.".	""."".. I'.	! i'.-T	.".	 ."". . ."'.".'.   3-64
              3.3.3.2 Beneficiation	   3-64
              3.3.3,3 Wastes	'. .	,.....[...   3-66
              3.3.3.4 Waste Management	   3.57
       3.3.4  COPPER	'.'.'.'.'.   3-69
              3.3:4.1 Geology of Copper Ores	   3-69
              3.3.4.2 Mining	   3_7j
              3.3.4.3 Beneficiation	"	!!!!!!!!!!!!   3-71
              3.3.4.4 Wastes and Waste Management	                              "   3.30
       3.3.5  IRON	,		!.'!!!!!!."'.'.'.'.'.'.'.'.   3-82
              3J.5.1 Geolpgy.of Iron Ores	           3.33
              3.3.512 Mining	 . .-	'.I'.'.'.'.'.'.'.'.  3-83
            "  3.3.5.3 Beneficiation	!!!!.!!!.!  3-84
              33^.4 Wastes and Waste Management	     	  3-87
       3.3.6   URANIUM	,	!....!.!..!..!!  3-88
              3.3,6.1 Cjeolpgy of Uranium Ores	" "  3.38
              3.3.6.2 Mining	;	','.'.[  3-89
              3.3.6,3 Beneficiation	                 3-go
  in in n in i i    ii ii MIIII in 11 n '"** M f M  -rrr      _* «»»    «•.'             •        *• ""*"*•""•*•••••" ••? oy
              3.3.6.4 Wastes and Waste Management	-	                   3.95
       33.7   OTHER METALS	."	'.'.	'.	I	."".".	'.'.'.'.'.'.'.'.'.'.'.'.'.'.I'.'.'.'  3-97
              3.3.7.J  Aluminum	  3.97
          .   3.3.7.2 Tungsten .	".' ."". . . '.'", ','", , . . ..............      3.93
              3.3.7.3  Molybdenum	.............[.[.]  3-99
              3.3.7.4  Vanadium	  '. ..'....  3-100
              313.73  Titariium ".	.'.'". .'.".	""."	".",".".".	'.'	~.'."..	'.''.	'	".'. '.	 .  ......... 3-100
             3.3.7.6  Platinum	                                        3 IQI
   Al'_COAL MINING	'.	I	M".1	;".	...!!!!!!!!!!!!!!!!!!!!!!!!!!! 3-102
       3.4.1  COAL FORMATION AND GEOGRAPHICAL DiSTRmtmoN	..'.'.'. 3-102
             3.4.1.1  Types and Composition of Coal	[ 3-102
                                                                       i
                                          ii                              September 1994

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 EIA Guidelines for Mining                         .                         Table of Contents


                3.4.1.2 Coal Provinces .......		3-103
                3,4.1.3 Trends  . . .	 .	  . 3-108
          3.4.2  SURFACE MINING SYSTEMS  	3-109
                3.4.2.1 Area Mining .	3-109
                3.4.2.2 Contour Mining	3-112
                3.4.2.3 Open Pit Mining	 3-115
                3.4.2:4 Special Handling . . . -.	3-116
                3.4.2.5 Equipment	3-116
          3.4.3  UNDERGROUND MINING SYSTEMS	3-116
                3.4.3.1 Development		 3-117
                •3.4.3.2 Extraction-	3-118
                3.4.3.3 Abandonment	3-123
                3.4.3.4 Pollution Control	 . 3-124
                3.4.3.5 Environmental Effects		3-125
     3.5   COAL PROCESSING	3-125
          3.5.1  BASIC PRINCIPLES	3-125
          3.5.2  COAL CLEANING TECHNOLOGY	,	 . 3-132
                3.5.2.1 Stage Descriptions	 3-137
                3.5.2.2 Process Flow Sheet for Typical Operations	 .  .~.	3-150
                    '
4. ENVIRONMENTAL ISSUES			4-1

    4.1   ACID ROCK DRAINAGE	".	 .	.4-2
          4.1.1  NATURE OF Aero ROCK DRAINAGE	4-3
                4.1.1.1  Acid Rock Drainage/Oxidation of Metal. Sulfides	 .  4-3
                4.1.1.2 Source of Acid and  Contributing Factors	4r4
          4.1.2  ACID GENERATION PREDICTION ...	4-7
                4.1.2.1  Sampling  . .	4-9
                4.1.2.2 Static Tests	  4-11
                4.1.2.3  Kinetic Tests.	  4-12
                4.1.2.4  Application of Test  Results in Prediction Analysis	  4-14
               . 4.1.2.5  Experience With Static and Kinetic Tests	  4-16
                4.1.2.6  Mathematical Modeling of Acid Generation Potential .	  4-17
          4.1.3  ARD DETECTION/ENVIRONMENTAL MONITORING	  4-21
          4.1.4  MITIGATION OF ARD	 .	  4-22
                4.1.4.1  Subaqueous Disposal		  4-23
                4.1.4.2  Covers	i	  4-24
                4.1.4.3  Waste Blending		.-	  4-24
                4.1.4.4  Hydrologic Controls	  4-24
                4.1.4.5  Bacteria Control	  4-25
                4.1.4.6  Treatment	  4-25
          4.1.5  SUMMARY OF FACTORS TO BE CONSIDERED IN EVALUATING POTENTIAL ARD
                GENERATION/RELEASE  ...:	:	  4-27
    4.2   CYANIDE HEAP LEACHING			 . .  4-28
          4.2.1  UNCERTAINTIES IN CYANIDE BEHAVIOR IN THE ENVIRONMENT	  4-29
                4.2.1.1  Cyanide in the Environment	J	;	  4-29
                4.2.1.2  Analytical Issues	  4-30
          4.2.2  POTENTIAL IMPACTS AND APPROACHES TO MITIGATION DURING ACTIVE LIFE	  4-31
                4.2.2.1  Acute Hazards	  4-32
                4.2.2.2  Spills and Overflows	.-	 ;	  4-32
                4.2.2.3  Liner and Containment Leakage	:	  4-34
          4.2.3  CLOSURE/RECLAMATION AND LONG-TERM IMPACTS	  4-35
                4.2.3.1  Closure and Reclamation	  4-35
                4.2.3.2  Long-term Environmental Concerns and Issues	• 4-36
                4.2.3.3  Assessments of Long-term Impacts	  4-38
                                                                               September 1994

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             <£ Contents 	""'	"""' '	'"•	' ''	'  ""	'"'             ''""	EIA ''
           4.3   STRyCjnLERAL^T.ABILrrY.pF TAJLJNGAMTOUNDMENTS	'	  4-39
                4.3.1  SEEPAGE AND STABILITY	  4-40
                43.2  SEEPAGE/RELEASES AND ENVIRONMENTAL PERFORMANCE	         	  4-42
        •   4.4   NATURAL RESOURCES AND LAND USES	!'."."!!. 4^3
                4.4.1  GROUNDWATER	  4-43
                4.4.2	AQUATIC LIFE	'.  .•.',"". 7V.,, *"'*.'......	'.".'	'".	."".1	.". ~'."".'	7."..'	.	]"".  '4^44"
                4.4.3  WILDLIFE	*..,,...........!..  4-47
'	'	"""	"""' ;"'	""i:::	:'4AA".	VEGETATION/WETLANDS 7".'..".	."7"! I.:.'.	.'".";	 ™,".~.'~.	'.'	".".':.'.	.'	  4.50
               4.4.5 . LAND USE	  4-52
                      4.4.5.1  Farmland	  4-52
                      4,4.5.2  Timber	'  4.53
                     •4.4.53  Grazing		  4.53
                      4.4.5.4  Recreation	,	;	  4.54
               4.4.6  CULTURAL RESOURCES	,	  4.54
	4.4,7	.AESTjHETICS ."....	,.. . . . .„.,.,. . .•	  4.54
          4.5  SEDIMENTATION/EROSION . .			  4.35
               4.5.1  BASIC EROSION PRINCIPLES	,. r		  4-56
               4.5.2  IMPACTS ASSOCIATED WITH EROSION/RUNOFF FROM DISTURBED AREAS  .........  4-58
               4.53  ESTABLISHING BACKGROUND CONDITIONS	  4-58
               4.5.4  PREDICTING SEDIMENT LOADINGS FROM NEW SOURCES	..........  4-61
                     4.5.4,1 Available Techniques/Model?	  4-62
                     ,4.5.4.2 Modeling Considerations  .  . _v. . r..'..^.._'.."r"~'.-'-.~'i!I.V.."......	-'I'•,',•""•"•',»..' 17". "4*63	
               4.5.5 _ SEDIMENT AND EROSION MITIGATION MEAsin^'T.'. .",1',,' i	I	.'.".	7'. 77.".'."...".""'.  4-64
	 	""4.5.5.1 Diversion Techniques	........	'....,..'.	  4-65
                     4.5.5.2 Stabilization Practices	  4-65
                     4.5.53 Structural Practices	.._...	..^.		,	._.	.,.	^	R, v. ,	  4-66
                     4.5.5.4 Contact Prevention  Measures/Reclamation Process	 .	  4-66
                  •  4.5.5.5 Treatment Techniques	  . ;	         4-69
          4.6   METALS AND DISSOLVED POLLUTANTS  	                	  4-69
       .   4.7   AIR QUALITY  /	.".".	".	".	I	7.\	\'".	7.'.".	'	;	" ' *""" "'	  4.73
          4.8   SUBSIDENCE	i ..,!.!!."!!•!!.'.*."  4-74
          4.9   METHANE EMISSIONS FROM COAL MINING AND PREPARATION  ...... . . . . . .   4-75
                                               ,,,!,"	I",'	I	","	:	:,'	:;	n	"	"	",",	.*..."   	,.
    I i^j y-^^,,^j™«^	-^	.^..- --..^ ^	^	-... ^	-	^ -^	^ ,-.^.-,~	, ,	,..,	-	,,-	,	^	 ......... ,  ^ 	
                                                                    .........
                	                                                         I
,          5.1   DETERMINE THE SCOPE OF ANALYSIS  .....	                              5-1
          5.2   IDENTIFY ALTERNATIVES  '.. I. .'.I  . . .'.".". . . V	I'.'.'.'.'.'.'.'.'.'.'.'.  5-2
              5.2.1   ALTERNATIVES AVAILABLE TO EPA	  5-3
              5.2.2   ALTERNATIVES CONSIDERED  BY THE APPLICANT	  5-3
              5.23   ALTERNATIVES AVAILABLE TO OTHER AGENCIES	                       5-4
          S3  DESCRIBE THE AFFECTED .ENVIRONMENT		.'.'.'.'.'.'.'.'.'.  5-4
              53.1  THE PHYSICAL-CHEMICAL ENVIRONMENT	  5-5
                    5.3.1.1 Air Resources  . :	[\[  5.5
                    53.1.2 Water Resources .  .".	 ..^.   5-6
                    53.13 Soils and Geology	      5-7
             5.3.2  BIOLOGICAL CONDITIONS	  5-8
                    53.2.1 Vegetation	  5-8
                    53.2.2 Wildlife .	  5-8
                    53.23 Ecological Interrelationships	5.9
             533  SOCIOECONOMIC ENVIRONMENT  	'.'.'.'.'.'.'.''.'.'.'.'.  5-9
                    53.3.1 Community Seryices	  5-9
                    533.2 Transportation'."..""". . . .. "."". . . . ...'"!, '. '."". . .""."..'.".". '.	  5-10
                    5333 Population	  ...........  5-10
                    5.3.3.4 Employment	',-,	,....        5-10
                    533.5 Healthand]Safity".""."r'."^	.".". ."7-7."'.  . ."". 7.\	I"!"!	'.	 . ]"""'""'"!  '.'.'.'.'.'.'.'.  5-11
                    53.3.6 Economic Activity	  5_U
                                    (ii	'	^	^l^1'  '"'	   ^	;" i(:	^	^/^	ir '	ij.	'


                                                iv                             September 1994

                                                                     1      '  '
          I,  ,                                            	    I	„	

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 EIA Guidelines for Mining   _ _                      Table of Contents


         5.3.4  LAND USE ..... ..................................... .....  5-1 1
         5.3.5  AESTHETICS ....... . ......................................  5-11
         5.3.e  GUTTURAL RESOURCES .........................                  5-12
     5.4  ANALYZE POTENTIAL IMPACTS ........... . .......... .... ..... .'..."  5.12
         5.4.1  METHODS OF ANALYSIS  ........................... . ..........  5-13
         5.4.2  DETERMINATION OF SIGNIFICANCE ................................ .  5-14
         5.4.3  COMPARISONS OF IMPACTS UNDER DIFFERING ALTERNATIVES ...............  5-16
         5.4.4  SUMMARY DISCUSSIONS  .................... , ........            5-16
     5.5  DETERMINE MITIGATING MEASURES  ....................    ........  5-17
     5.6  CONSULTATION AND COORDINATION  .......... '. ....................  5-18
 6. STATUTORY 'FRAMEWORK
    6.1  CLEAN WATER ACT ................................                6-1
    6.2  CLEAN AIR ACT ......................... ...... ........        * " 6-15
    6 3  RESOURCE CONSERVATION AND RECOVERY ACT ...... ..........        6-17
    6.4  ENDANGERED SPECIES ACT ........... . . . ; ....... ..........        6-19
    6.5  NATIONAL HISTORIC PRESERVATION ACT . ........... . ......... ...     6-20
    6.6  COASTAL ZONE MANAGEMENT ACT ................................  6-21
    6.7  EXECUTIVE ORDERS 11988 AND 11990 ......................            6-21
    6.8  FARMLAND PROTECTION POLICY ACT ....... . : ...........             6-22
    6.9  RIVERS AND HARBORS ACT OF 1899 ........................           6-22
    6.10  SURFACE MINING CONTROL AND RECLAMATION ACT .................. .  6-23
         6.10.1 PERMITTING PROGRAM FOR ACTIVE COAL MINING OPERATIONS ......... .....  6-23
         6.10.2 ABANDONED MINE LANDS PROGRAM ..................               6-25
    6.11  MINING LAW OF 1872 ....................................      : "  6-26
    6.12  FEDERAL LAND POLICY MANAGEMENT ACT . . / .......... ........ .....  6-27
    6.13  NATIONAL PARK SYSTEM MINING REGULATION ACT ____ ........        6-29
    6.14  ORGANIC ACT; MULTIPLE USE AND SUSTAINED YIELD ACT; NATIONAL FOREST
         MANAGEMENT ACT .......................... ... ...........       6-30
    6.15  MINERAL LEASING ACT; MINERAL LEASING ACT FOR ACQUIRED LANDS ". '. '.'. '. '.  6-30
    6.16  COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY
         ACT  ................................... ....................  6-31
    6.17  EMERGENCY PLANNING AND COMMUNITY RIGHT-TO-KNOW ACT  ..           6-32
    6.18  WILD AND SCENIC RIVERS ACT ............................... ]  " :  6-32
    6.19  FISH  AND WILDLIFE COORDINATION ACT ..............         ........  6-33
    6.20 FISH  AND WILDLIFE CONSERVATION ACT  .........                .   *    6-33
    6.21 MIGRATORY BIRD PROTECTION TREATY ACT ..................... '.'.'.'.  6-33
7.  REFERENCES
                                                                  September 1994

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     Table of Contents
                                                                         EIA Guidelines for Mining
                                  	-	 • •• LIST OF EXHIBITS
    Exhibit                   -                                                                 Page

    Exhibit 1-1.  Standard Industrial Classification Codes for the Metal Mining Industry  	  1-4

    Exhibit 2-1.  NEPA Environmental Review Process for Proposed Issuance of New Source
                NPDES	Permits	,	.	.	,	.„.,„,„„,„,„„, ,„„,,.-. .'	          2-5
    Exhibit 2-2.  Model Schedules for EAs and EISs for Proposed Issuance of New Source	" ' ' '
                NPDES Permits	.	  2-18

  .  Exhibit 3-1.  Twenty-Five Trading Gold-Producing Mines hi the United States, 1991	  3.31
    Exhibit 3-2.  Twenty-Five Leading Silver-Producing Mines in the United States, 1991  . . . . .  . . . . .  .  3-32
    Exhibit 3-3.  Materials Handled at Surface and Underground Gold Mines, 1988            	  3.34
  .Exhibit 3-4.  Chemicals Stored and Used at Gold Mines	•..'."!.'.".".'!.'."  3-36
    Exhibit 3-5.  Gold Mining and Beneficiation Overview	'.'.'.'.'.'.'  3-38
    Exhibit 3-6.  Gold Ore Treated and Gold Produced, By Beneficiation Method, 1991 . .  . . .  . .  '.'.'.'. '.  '.  3-39
   Exhibit 3-7.  Steps for Gold Recovery Using Carbon Adsorption	  	  3_42
   Exhibit 3-8.  Chemicals Used at Lead-Zinc Mines	..........!....]....  3-68
   Exhibit_34>,  Leading Copper Producing Facilities in the United States	    	3-70
   Exhibit 3-10.  Copper Flotation Reagents  	!!....!.!.!.......       3-72
   Exhibit 3-11.  Characteristics of Copper Leaching Methods  	..............	  3.74
  Exhibit 3-12.  Typical Solvent Extraction/Hectrowinning (SX/EW) Plant . . . . .  . . '.'.'.'. '. ......     3-78
  Exhibit3-13,  Types of Coal and Relative Percentages of Constituents ...  	:•••••	
  Exhibit	3-14.	Coal	Provinces,	of the United States	!.'."!.".'.'].'!'*"" 3-104
  ^x^|i.l~ll,:	Summary of Environmental Considerations by Province       '          	3 IDS
  Exhibjs 3-16.  Area Mining With Stripping Shovel	].*.".'	3_!10
  Exhibit 3-17. Moantaintop Removal With Head-of-Hollow Fill	slin
  Exhibit 3-18. Box-Cut Mining Operations	  '  	     3 113
  Exhibit 3-19. Block-Cut Mining Operation	'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'	
  Exhibit 3-20. Operations in Conventional Room and Pillar Mining  	
  Exhibit 3-21. Longwall Mming System		.".'.'	
  Exhibit 3-22. Ash and Sulfur Reduction Potential of U.S. Coals] Vol. I p. 395, Eastern
                Regions U.S. Department of Energy  ....                                         •» 1
  Exhibjt3-23. Washability Partition Curve	    		3"}
  Exhibit 3-24. Coal Preparation Plant Processes	      	3"13-.
  Exhibit 3r25, Typical Coal Cleaning Facility'	'.'.'.'.'.	3.134
  Exhibit 3-26. Typical Circuit for Coal Sizing Stage  ...!!!!...!....%/!!..!!!	3-135
  Exhibit 3-27. Metric and English Equivalents of U.S. Standard Sieve Sizes and Tyler Mesh	
	Sizes	                         '                          -i fid
  E^^itS^S. Ty^ic^i Soce^ Qua^^ for a^oi^a(»b"T)Ver HouV"Q)al CleaninV	
               Facility	                 *              3 13_
  Exhibit 3-29.  Typical Three-Stage Crusher System for Raw Coal Crushing	" "	" " 3-138
  Exhibit 3-30.. Single-Roll (a) and Double-Roll (b) Crushers for Sizing of Raw Coal    	3-139
  Exhibit 3-31.  Feed Characteristics of Unit Cleaning Operations for Sizing and Separation of	
               Cijusfaed Coal	                                        ,  141
  Exhibit 3-32. Typical Circuit for Dense Media Coal Cleaning	3~142
  Exh|b|t 3-33. Typical Circuit for Jig Table Coal Cleaning	             	3  144
  Exhibit 3-34. Typical Air Table for Pneumatic Coal Cleaning	!.!....!.!!.	3^45
  Exhibit 3-35. Typical Circuit for Pneumatic Coal Cleaning	'.'.'.	3-146
  Exhibit 3-36. Desirable Chemical Characteristics of Make-Up Water for Coal Cleaning	
               Processes	                                3 147
  Exhibit 3-37. Typical Product Dewatering Circuit for Coal Cleaning ".'.'.'.'.'.'.'.'.'.'.'.'.I'.'.'.'.'.'.'.'.  3^48
                                                                                              i
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                                                VI
September 1994

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 EIA Guidelines for Mining
Table of Contents
 Exhibit 3-38.  Typical Moisture Contents of Dried Product from Selected Drying Operations
               in Coal Cleaning Facilities	;	3-149
 Exhibit 3-39.  Thickener Vessel for Dewatering of Coal Cleaning Products	3-150
 Exhibit 3-40.  Schematic Profile of a Sieve Bend Used for Coal Sizing and Dewatering  	3-151
 Exhibit 3-41.  Profile View of a Coal Vacuum Filter  	3-152
 Exhibit 3-42.  Thermal Dryer and Exhaust Scrubber . . .	3-153
 Exhibit 3-43.  Typical Flash Dryer  	,	3-154
 Exhibit S--44.  Coal Cleaning Plant Flow Sheet for Coarse Stage Separation and Dewatering  . . '.	3-156
 Exhibit 3-45.  Coal Cleaning Plant Flow Sheet for Fine Stage Separation and Dewatering . . . ;	3-157
. Exhibit 3-46.  Coal Cleaning Plant Flow Sheet for Sludge (Slime) Separation and Dewatering	3-158

 Exhibit 4-1. Summary of Static Test Methods, Costs, Advantages, and Disadvantages . . :	  4-13
 Exhibit 4-2. Summary of Some Kinetic Test Methods, Costs, Advantages, and Disadvantages	  4-15
 Exhibit 4-3. Stability of Cyanide and Cyanide Compounds in Cyanidation Solutions	 :	  4-30
 Exhibit 4-4. Typical Pollutants Associated With Hardrock Mining Operations	  4-71
 Exhibit 4-5. Typical Pollutants Associated With Coal Mining Operations	  4-72

 Exhibit 6-1. Major Federal Statutes Generally Applicable to Mining Operations   	6-2
 Exhibit 6-2. New Source Performance Standards for Coal Mining Category
               (40 CFR Part 434)	1	  6-9
 Exhibit 6-3. New Source Performance Standards for Mine Drainage, Ore  Mining and
               Dressing Category (40 CFR Part 440,  Subparts A-K and M)	  6-10
 Exhibit 6-4. New Source Performance Standards for Mills and Beneficiation Processes, Ore
            .   Mining and Dressing Category (40 CFR Part 440, Subparts A-K and M)	 .  6-",.'.
 Exhibit 6-5. Examples of Discharges From Ore Mining and Dressing Facilities
               That Are Subject to 40 CFR Part 440 or to Storm Water Permitting	  c-.
                                                 VII
 September 1994

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     Guidelines for M"""g _ _ __ _    Introduction

                                  1.  INTRODUCTION
 The National Environmental Policy Act of 1969 (NEPA, 42 U.S.C §4321 et seq.) was the first of
 what has come to be an array of statutes whose individual and collective goals are the protection of
 the human and natural- environment from a variety of impacts that human activity can have.  NEPA
 introduced the requirement that Federal agencies consider the environmental consequences of their
 actions and decisions as they carry out then* mandated functions.. For "major Federal actions
 significantly affecting the quality of the human environment," the Federal agency must prepare a
 detailed environmental impact statement that assesses not only the proposed action but also reasonable
 alternatives.

 The Federal Water Pollution Control Act (33 U.S.C. §§1251-1387), better known as the Clean Water
 Act, seeks to restore and maintain the chemical, physical, and biological integrity of the Nation's
 waters.  One of the major mechanisms by which the Clean Water Act is to attain that goal is the
 requirement that all point source discharges of pollutants to waters of the United States be controlled
 through permits issued under the National Pollutant Discharge Elimination System (NPDES).
                                                                                      *
 The Clean Water Act [§51 l(c)(l)] also requires that the issuance of a NPDES permit by the
 Environmental Protection Agency (EPA) or authorized States for a discharge from a new source be
 subject to NEPA. In 1979, EPA established the regulations by which it applies  NEPA in such cases:
 "Environmental Review Procedures for the New Source NPDES Program," 40 CFR 6 Subpart F.
 These procedures require EPA to prepare a written environmental assessment  based on information
 provided by the new source NPDES permit applicant and other available documentation.  If the
 environmental assessment concludes that no significant impacts will result from  issuance of the new
 source NPDES permit, EPA issues a Finding of No Significant Impact (FNSI).  If the assessment
 concludes that there may be significant environmental impacts that cannot be eliminated by 'changes hi
.the proposed project, EPA must prepare (or participate hi the preparation of) an environmental impact
 statement that contains the information and analyses described in 40 CFR Part 6 Subpart B and
 conforms with Council on Environmental Quality regulations (40 CFR Part 1502) governing NEPA
 compliance.                 •

 In preparing the environmental assessment, EPA relies on information and analyses provided by the
 applicant for the new source NPDES permit in an "environmental information document," or EID.
 The scope and content of an EID is determined by EPA hi consultation with the applicant, with the
 regulatory caution that EPA "...keep requests for data to the minimum consistent with his
 responsibilities under NEPA" [40 CFR 6.604(b)].
                                             1_1                              September 1994

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       *ntrodnctlon	                                            EIA Guidelines for Mining
       1.1     PURPOSE OF ENVIRONMENTAL IMPACT ASSESSMENT GUIDELINES

      Following the promul|ation of New Source Performance Standards for new source discharges in the
      late 1970s and early 1980s, EPA prepared a series of "Environmental Impact Assessment Guidelines"
  	for W	in	determining	the	scope	and	consents	of HDs	for	new	source,	NPDES. permits for •facilities in
      specific'industries.  The guidelines also were intended to assist EPA staff in reviewing and
      commerSng on applicants' BID information and in preparing, overseeing the preparation of, or
      commenting on environmental assessments and environmental impact statements
        I     '          .  '"Ill""	'I*1	I	   ' 	'•I""	I"	I'1	sed ffijg 2*$^ 5?y have. Because many of the potential impacts, and the information and
     analysts needed to assess impacts* are common to metal and coal mining me topics covered by the
     three 3™™*® guidelines documents have been combined into this single document.
                                                                         '
    These guidelines are expressly intended to provide background information for EPA staff to assist
    tfa*m'ln consulting with and directing new source NPDES permit applicants in the- scope and contents
    of E[£>s *??_ !? * 55!???!10? !° ?5?!5! H«S M .Modifying and evaluating the potential impacts of
    JfS^ ..... 5^21 ..... E25S: ............... i£i ...... SSEStes ...... several ...... oto audiences ...... for .these guidelines: EPA staff
    ^° r?fi!!! ...... — ...... SS^ ....... 2n,.5te5^5»L!ffi?^i' ..... ?m^onmen|al.|inpact  statements and regulations
    pursuant to §309 of the Qean Air Act; other EPA staff who deal with the ruining industry and its
    eavfronmental JBpactsj gew.sonoe. NPOES permit applicants who must prepare EIDs for EPA; other
    Federal agencies responsible for regulating or overseeing the mining industry; and State, local, and
    foreign government environmental officials.  Officials in States tha| hayesfeeen authorized to
    m5)1
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  EIA Guidelines for Mining	^	     Introduction

  These guidelines supplement the more general document, Environmental Impact Assessment
  Guidelines for Selected New Source Industries, which provides general guidance for preparing
  environmental impact assessments (EIAs) and presents impact assessment considerations that are
  common to most industries,- including mining.

  1.2    SCOPE OF THE MINING INDUSTRY

  The ore mining and dressing (or beneficiation) industry is composed of mining facilities that remove
  raw mineral ores from the earth, and of mill facilities that separate the mineral ores from overburden
  and waste rock removed during mining activities. The industry also includes mill facilities that
  further concentrate and purify metals in the ore to a condition specified for further processing
  (smelting and/or refining) or for incorporation as a raw material by another industry. The mining and
 beneficiation of various mineral ores occurs nationwide, and is viewed as critically important to the
 Nation's economy since it provides the raw materials on which many other industries rely.

 The metal mining industry is identified as Standard Industrial Classification (SIC) Major Group 10.
 This industrial.group includes facilities engaged in mining ores for the production of metals and also
 includes all ore dressing (or beneficiation) operations, whether performed at mills operating in
 conjunction with mines or at mills operated separately. These 'include mills that crush, grind, wash,
 dry, sinter, or leach ore, or that perform gravity separation or flotation operations.

 EPA has promulgated effluent limitation guidelines for discharges  of pollutants from existing and new
 sources hi the Ore Mining and Dressing Point Source Category (40 CFR Part 440). These effluent
 limitation guidelines provide numeric limitations for discharges from mines and mffls in various
 industry subcategories (see also Chapter 5).  Exhibit 1-1 shows the SIC categories covered by this
 industrial group and the subcategories for which EPA has promulgated effluent limitation guidelines.

 The coal mining industry is composed of facilities that mine coal of any rank from the earth, and of
 preparation plants that clean or otherwise prepare the coal for combustion and other uses,  the coal
 mining industry is identified as Standard Industrial Classification (SIC) Major Groups 11 (anthracite)
 and 12 (bituminous and lignite).  These industrial groups include facilities that are engaged in mining
 coal and preparation plants that operate in conjunction with mines or separately.

 EPA has promulgated effluent limitation guidelines for discharges of pollutants from existing and new
 sources in the Coal Mining and Preparation Plant Point Source Category (40 CFR Part 434).  These
 effluent limitation guidelines provide numeric limitations on discharges from mines (with separate
 standards for acid and for alkaline discharges), preparation plants, and areas of mines that are being
reclaimed.
                                             1-3                              September 1994

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     Introduction
                                                                     EIA Guidelines for Mining
In hill
1"
Exhibit 1-1. Standard Industrial Classification Codes for the Metal Mining T^HMC^.
SIC
1011
1021
1031
1041
1044
1051
1061
1092
1094
' 1099
Type of Ore .
Iron Ores
CopperOres
Lead and Zinc Ores
Gold Ores •
Saver Ores
Bauxite and Other Aluminum Ores

Ferroalloy Ores, except Vanadium
Mercury Ores
Uranium, Radium, and Vanadium Ores
Other Metal Ores
Subpait Within 40 CFR Part 440
Subpart A
Subpart J
Subpart J
Subpart J (lode)
Subpart M (placer)
Subpart J
Subpart B
Tungsten: Subpart F
Nickel: Subpart G
Molybdenum: Subpart J
Subpart D
Subpart C
Subpart H (vanadium when mined
alone— reserved)
Antimony: Subpart I
Plathmm: Subpart K (reserved)
Titanium: Subpart E
•—•—•••••••••••I '



•
  13    ORGANIZATION OF GUIDELINES
  The remainder of this document is organized as follows. Chapter 2 describes NEPA requirements
  and Provisions as they apply to issuance of new source NPDE§ permits.  Chapter 3 presents
  ...... ^SSSiiffliSS ..... Miff mdustty-  This ...... chapter is intended to give the reader background
  information on the operations that take place on mine sites.  The apparent simplicity of mining--
  amoving OI^ .^5.^?..^*^B* *f? 5™?5;!!3S to* valuable product from the ores— disguises
  what *f m I^&£fi™^^OTpi^yi ........... As ...... a ..... result, ...... some ...... understanding of the nature of mining
  operations is necessary in any assessment of the potential environmental impacts and in identifying the
  infonnationiradaiialyses that are                                      Metal minuig and
  beneficianon arc described in the first three subsections of Chapter 3.  The first two describe,
                                    operations that are common to the industry; the third describes
  «•* rf_*?. SBJor Industry sectors, with particular regard to the mining and beneficiation operations
  that are unique to the individual sector. This third subsection focusses on the industry sectors which
  are most important to the U.S. mining industry, including gold, copper, iron, lead-zinc, and uranium.
                                             1-4
                                                             September 1994
in ,1
riii
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i	in
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ill 111 I ill III

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 EIA. Guidelines for Mining	    Introduction

 Sectors for which EPA has promulgated effluent limitation guidelines but in which there are currently
 very few active mines (e.g., aluminum, molybdenum, platinum, tungsten) or no active or anticipated
 mines (e.g., antimony, mercury) are also.described, but hi less detail.  Following the subsections on
 metal mining are two subsections that describe coal mining and coal preparation, respectively.. All of
 the subsections in this chapter describe the major operations that take place and identify the major
 environmental concerns of these operations.

 Chapter 4 then describes in some detail several of the major environmental issues and impacts that are
 of most concern when evaluating the potential major impacts of proposed mining operations.
 Separate subsections hi this chapter describe each of a number of major potential impacts and the
 circumstances that can lead to their occurrence.  These sections also describe the types of information
 and analyses that are necessary to identify whether these impacts are of concern for a particular
 operation, to evaluate these potential impacts and then* significance, and to identify and evaluate
 possible mitigation measures.

 The process of analyzing impacts within the context of NEPA and new source NPDES permits is
 described in Chapter 5. Separate subsections describe each of the major steps hi the impact analysis.
 Chapter 6 then provides information on the major Federal environmental and natural resource
 management statutes that directly affect or that regulate mining operations.  The purposes and broad
 goals of each of these statutes are described, along with a brief indication of the requirements
 imposed by the statute and the^implementing agency's regulatory or consultation programs.

 Finally, references cited hi the document are listed hi Chapter 6, as are a number of other valuable
 references.  Appendix A presents an outline, in the  form of a "checklist," of the types of information
and analyses that should go into an environmental information document.  Appendix B presents a
glossary of terms.
                                             1-5                              September 1994

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  EIA. Guidelines for Mining	^	      NEPA Requirements and Provisions


                   2. NEPA REQUIREMENTS AND PROVISIONS

 2.1    OVERVIEW      .

 NEPA serves as the basic national charter for environmental protection.  Section 102 of NEPA
 establishes environmental review requirements for Federal actions. These reviews or impact
 assessments are required to be broad in scope, addressing the full range of potential effects of a
 proposed action on the human and natural environment.  A general framework for implementing these
 requirements is presented in regulations issued by the Council on Environmental Quality (CEQ).
 Federal agencies, in turn, have developed their own rules for NEPA compliance that are consistent
 with the CEQ regulations but address then* specific missions and program activities.  Over the past 25
 years, the NEPA framework for environmental review of proposed Federal actions has  been
 substantially refined, based on further congressional directives, action by CEQ, and an .extensive body
 of case law.

 Congress has determined that most EPA activities are exempt from impact assessment requirements
 under NEPA.  In the case of EPA's water quality programs, Section 511(e) of the Clean Water Act
 (CWA) clearly specifies that actions taken by EPA under the Act shall not "be deemed a major
 Federal Action significantly affecting the quality of the human environment within the meaning of the
 National Environmental Policy Act of 1969." However,  Congress did make two important exceptions
 to this exemption:

      (1)  the provision of financial assistance for the construction of publicly owned treatment works
      (2)  the issuance of NPDES permits for new sources as defined hi Section 306 of the CWA.

 The specific reference to NPDES new source permits makes clear EPA's responsibility to review
proposed permit issuance actions from the broader perspective of the NEPA environmental assessment
framework.

Since EPA does have responsibility for conducting environmental reviews for some types of proposed
activities,  the Agency has developed and codified its own  set of NEPA procedures. These
procedures, which are found at 40 CFR Part 6, have been revised a number of times. Some of the
relevant steps in the course of the development of EPA's current regulations are as follows:

      •   Initial EPA proposed rulemaking setting forth procedures for the preparation of EISs (37 FR
         879;  January 20, 1972)

      •   Interim EPA regulations for Part—Preparation of Environmental Impact statements (38 FR
         1696; January 17, 1973)
                                           2-1                            September 1994

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                                                                                   ••1	
            NEPA Requirements and Provisions	   KTA Guidelines for Mining
                 •   Notice of proposed rulemaking—Preparation of EISs (39 FR 26254; July 17, 1974). This
                     proposed rulemaking reflects substantial public comment on the interim regulations as well
                     as additional CEQ requirements. The rulemaking addresses EPA's nonregulatory programs
                     only.                            •
                                                                                     ••'.•"

                 •  ' Final EPA regulations on the preparation of Environmental Impact statements (40 FR  •
                     16814, April14,1975).  Althoughprocedures for new source NPDES permits are not
                    'included"uTthis rulemddiiigTgp^ ^^in the'preamble that such regulations will be
                     subsequently issued in 40 CFR Part 6.
                           	 •' ,   . ,  -     v   	• ,    .       .  .       ••       j •   .  ^  .  : '
                 •    Preparation of Ifovfronrnental Impact Statements, New source NPDES permits (42 FR 2450,
                 	J^anuarj	11,	1977).	Presents an	outline	for	the preparation of EISs for proposed new source
                	permitting action.
                                                                                     i  ..'.•.
                 *   Proposed rule—Implementation of Procedures on the National Environmental Policy Act (44
                    FR 35158; June 18, 1979). In response  to major revision of CEQ's regulations in 1978,
                    EPA revises its procedures accordingly.  The revised procedures include streamlining and
                    clarification of procedures in general.  In addition, requirements for NPDES new source
                    permitting actions were substantially revised and presented as Subpart F of the proposed
                    rule.,      '         •                                    •   •     ','.''

                •   Final rule—Implementation of Procedures on NEPA (44 FR 64174, November 6, 1979).
                    Issues raised during promulgation include limitation of construction activities during
                    permitting process and environmental review and the conditioning .or denying or permits
                    .based on factors identified during the NEPA review process.
                          i         .                         •.-......,,	  .     |
                *   Minor changes to Subpart F,. involving die changing of citations, were made on September
                 '   12, 1986 (51 FR 32606).    "
          2.1.1	EPA REQUIREMENTS FOR ENVIRONMENTAL REVIEW UNDER NEPA
          Illl  nil llllllllllllll I III1 111 III VIII111 11 HI Pill I IIIII llllllli n i liiiiiiii iiiiiiiiiiii iiinminnm • i in in nil i iiiiiiiiiiii n iiiiini i nn •  i      —-— ««•  *•» »» «**•r_rim * *»«• A*.
          EPA's current National Environmental Policy Act Procedures (40 CER 6) outline the Agency's
          policies and processes for meeting environmental review requirements under NEPA. Subpart A of
          && Procures provides/an overview of the Agency's purpose and policy, institutional responsibilities,
          and general procedures for conducting reviews.  Subpart A outlines EPA's basic hierarchy of NEPA
          compliance documentation as follows:


                •  Environmental Information Document (ETO), which is a document prepared by
                   applicants, grantees, or permittees and submitted to EPA. This document must be sufficient
                   in scope to enable EPA to prepare an environmental assessment.
	 '*  ;:	SliFJiil^ial	J^essjnent	(EA), which is a concise document prepared by EPA that
                   provides sufficient data and analysis to determine whether an EIS or finding of no
	gignpcan^impact is required.
IllljIH I i i HIP1     IjllliU	               -
I!5S'	"'!'	„'!'!?   "i  Sl'^n'SpffiiS                                         intent 'to	p:repare '^"^	~
                   which is published in the Federal Register, reflects the Agency's finding that the proposed
                                                      2-2                              September 1994

                                                       in  n nn ii   i  i iiiiiiiiiiii     1111  i iiillii ill n  iiiiiii  i i ll nn ill i  li i  i ii|ii in i  i in in  nn in i  iii|ii(i|ii

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E1A. Guidelines for Mining/	NEPA Requirements and Provisions

         action may result in "significant" adverse environmental impacts and that these impacts can
         not be eliminated by making changes in the project.

      •  Environmental Impact Statement (E3S), which is a formal and detailed analysis of
         alternatives including the proposed action, is undertaken according to CEQ requirements
         and EPA procedures.

      •  Finding of No Significant Impact (FNSI), which announces EPA's finding that the action
         analyzed in an EA (either as proposed or with alterations or mitigating measures) will not
         result in significant impacts. The FNSI is made available for public review, and is typically
         attached to the EA and included in the administrative record for the proposed action.

      •  Record of Decision (ROD), which is a statement published in the Federal Register that
         describes the course of action to be taken by an Agency following the completion of an
         EIS.  The ROD typically includes a description of those mitigating measures that will be
         taken to make the selected alternative environmentally acceptable.

      •  Monitoring,  which refers to EPA's responsibility to ensure that decisions on any action
         where a final EIS is prepared are properly implemented.

Subpart B of EPA's Procedures provides a detailed discussion of the contents of EISs.  This subpart
of the text specifies format and the contents of an executive summary, the body of the EIS, material
incorporated by reference and a list of preparers.

Subpart C of the Procedures describes requirements related to coordination and other environmental
review and consultation requirements. NEPA compliance involves addressing a number of particular
issues, including (1) landmarks, historical, and archaeological sites; (2) wetlands, floodplains,
important farmlands, coastal zones, wild  and  scenic rivers, fish and wildlife, and endangered species;
and (3) air quality. Formal consultation with other agencies may be required,  particularly in the case
of potential impacts on threatened and endangered species and potential impacts on historic or
archaeological resources.                .      •

Subpart D of the Procedures presents  requirements related to public and other Federal agency
involvement.  NEPA includes a strong emphasis on public involvement in the review process.
Requirements are very specific with regard to public notification, convening of public meetings and
hearings, and filing of key documents prepared as part of the review process.

Subpart F presents environmental review procedures for the New Source NPDES Program. This
Subpart specifies that the requirements summarized above (Subparts A through D) apply when two
basic conditions are met: (1)  the proposed permittee is determined to be a new source under NPDES
permit regulations; and (2) the permit would be issued within a State where EPA is the permitting
authority (i.e., that State does not have an approved NPDES program in accordance with  section
402(b) of the CWA). This Subpart also states that the processing and review of an applicant's
                                             2-3                              September 1994

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                                                                                        in i inn n n i inn i in  n  1 1 n inn n 1 1 1 1 n i illinium iiiiiiiiiiii|ii iliii||||i|lli iiiiiii i inn i n i
                                                                                        n in niinnii L  i  i n iiiiiiiiiiiiliiiiii|iiii nil i nil i i

       ...............
ifepA Requirements and Provisions
                                                                            EIA Guidelines for Mining
  in  in in   iii  iiiiiiiiiiii iiiiiii iiii i in (in nil i iiiiiiiiiii
                                 ii in i mi iiiiiii i ii i 11 in i
                                                                        IIIIIIIIIIII 111 I III 111 111 I
          NPDES permit application must proceed concurrently with environmental review under NEPA.
          Procedure? for the environmental review process are outlined. Subpart F also provides criteria for
          determining when EISsmust be prepared, as well as rules relattof to the preparation of RODs  and
          monitoring of compliance with provisions incorporated within the NPDES permit. (A more detailed
          discussion of the enYhgimejiM review process and triggers for certain specific environmental
         assessment requirements are presented later in this chapter.)
         The remaining Subparts of the EPA Procedures (i.e., Subparts E, G, H, I, and J) address aspects of
         E?A'Jnmei*ewP^that.??6., n°t rekyapt to these guidelines for the proposed
                                                                                 iff
'i	mmm	i	»
          *
                                                       NEW SOURCE NPDES PERMITS
        ^ .......         ...... bl ...... Exhibit ..... 2:ls ....... the ...... 1^ review ...... of proposed new source permitting actions and the
        process of NPDES permit issuance are to occur concurrently.  However, completion of the
        environmental review-either through the issuance of a FNSI or the issuance of a ROD-is to precede
        actual permit issuance or denial.
         	JE	SS™,	a	^22&6.fSi^S»	EPA	IS5I	SSS	ensure	that	the	two primary conditions
^jj:]ii •. $# ^Sg61" NEPA environmental review have been met.  EPA Regional office staff then would
,™	i™..iS$pi!S	ll£	il	P«15!	Applicant	to	determine,,the	scope of the information document; and upon
'.1™" *£S£X	fejE	SS^aPP11031*, to set time limits on the completion of the review process consistent
        ^5 55 *SOi-8-  (Jnfonnation required from permit  applicants is addressed in more detail later
	"  in this chapter.)
im'"SM  ^^'Jlii^ii	i	»mm iiiiiii	111	i	i	'.ill	1:1	iiiiiii	ii!Mjt*f;;?!& ''iirdii1  '           •                                 	WM'-^	^^

i£u™:,9Bffi	lilt...!*111111 applicant has	submted Ae	EID,	EPA	Regional office staff must review the
                              the 'IP1*??11? ^onS with iPy other available information that is relevant.
                                          a written EA which identifies alternatives, including the
                              a ^^B??? ^ysis of the potential impacts of these alternatives, and
                any mitigation measures that could be (of will be) undertaken to address potential significant
       impacts.
                                                             	' „,'	i	
       1	            '                                       	" "r"	;"	•"	'	"	-""I	'	:	:	:	
       The EA will result in one of two possible outcomes. If the review indicates that the proposed
      ,,, issuance .ofJhe ,,newsource permit is likely to result in "significant" adverse impacts that cannot be
       avoided through changes in the proposal, then EPA must initiate the more formal process of EIS
       PIffSratio1!: ShouldtheMrcBgw indicate that the proposed action would be unlikely to result in
       significant adverse impacts  or that those impacts could be avoided by modifying the proposal, EPA
       would issue a FNSI.


                                                	I	;	:	,^|
                                                                                    September 1994
                                                                            -,

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EIA Guidelines for Mining
                                 NEPA Requirements and Provisions
    Exhibit 2-1. NEPA Environmental Review Process for Proposed Issuance of New Source
                                           NPDES Permits
          '&&*
 PriawCoadl*n*Oi*tTngg*NEPAEmrin>aa*itMltton*r I

>PfDVW«wNPOESpwintdMwmiMdtt)b«'nMriouRB<      I
• Pwmrt would b* i**u*d in • eat* when EPA » pwmiaing authority I
                                      • SoepJn0M*t*tmin«tion of infomuiion ra
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            NEJPA Reqmnanenls and Provisions              	EIA Guidelines for Mining
            A FNSI, which identifies any mitigation measures necessary to make a project environmentally
            ^^fe* »wstfe^available for public review (typically through publication in the Federal
           Register) and comment before issuing the permit.
          ll  ii i i iiiiiii in n ill i in i in mi  i inn in in nil iiiii inn 11111  i n i  i iiiii n i n n in in in iiii| n n ii inn nil    i nil i i n i i mini i mini MI      in   inn mi  i ••• inn i  i iiiiNnniininiiii|| nn inn iipinniii1 i1  IP piiiiiiiiiinn ih  n  in mn
          l! "'"" ' """"""""" """""" "" ' iiiiiiiiiiiiiiiiiii ||||||||l|n|  Ml   l|i|  ii iiiii in n    n in  i • inn nil in in nn i i    i      i in HI  n in in n inn   n in i iiiinnn iiiiiwi'inn 11	i	
           The process of preparing an EIS is a more complex and formal process that begins with EPA's
           consultation with any other Federal agencies that may be involved in the project.  Should EPA be
           designated as "lead" agency forjheEE5, EPA would then begin the process through the publication
           through EPA's Office of Environmental Review of an NOI in the Federal  Register.  EPA also may
           consult with the permit applicant at this point to discuss the option of preparing the EIS through a
           "third-party method." If the applicant and EPA agree on this method (and this agreement must be
           expressed in writing), the applicant would then engage and pay for the services of a third-party
                            EE^	!?:	^	™	*&***?!*,	will	elminate	the need for further independent
                            l	bl	*y?PJfcH*:	^A,	i?	consultation	with the	applicant, would choose the
                          	SSI	PEZls	&E2E2*!:	^closure	statements	attesting to a lack of financial or
               	          	SS2.2	SS	SHgSSS.SllS	S§8	SB&	¥fluld	manage the contractor and would
                           of the process, a preliminary set of alternatives would be identified, based on
T"1:'-.1:	"....-several perspectives:       "             '
                                         by the applicant               .-
                   Altemaliyes available to EPA
                   Alternatives available to other agencies with jurisdiction over the facility.
         f16*1 f ** sc°Pmg P10^' wni* Solves identifying key issues, refining the list and description of
         f111!111?!!!5:	?2	      	EEE!	g=55£5	ISC	HE	daassi	analyses that win be required to complete
         the assessment.  Public involvement and interagency coordination are important parts of the scoping
        ,	5!^:	!*S	5liE!SZ	EE°ly«S	US	convening of a scoping meeting attended by interested parties
         If a third^arty contractor is to prepare the EK, the contractor is not to begin work until after the
         scoping meeting  is held.
                   the scoping process, the potential impacts of alternatives, including the proposed action,
         are analyzed and a Draft EIS (DEIS) is prepared in accordance wifh strict format and content
         TOJUiremen£S- *> fc*«w^ff MSpreparation,a numberof specific coordination and consultation
         requirements must be met. These incjude formal consultation with the U.S. Fish and Wildlife Service
         (and/or the National Marine Fisheries Service) regarding threatened and endangered species issues as
         Wdi as formal consultation with the State Historic Preservation .Offices (SHPO) on any relevant
         cultural and historic resource issues.
                                                                                       September 1994

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 EIA Guidelines for Mining                 	        NEPA Requirements and Provisions

 After the DEIS is. reviewed internally by EPA, the public and interested parties are notified of its
 availability through a. Federal Register notice, notices hi local newspapers, and letters to participants
 hi the scoping process. EPA also would conduct one or more public hearings to further solicit
 comments on the DEIS.

 Following the comment period for the DEIS, EPA (or the third-party preparers as directed by EPA)
 would respond to all comments and would prepare the final EIS (FEIS). After internal EPA review
 of the FEIS,  notification again is made through the Federal Register, notices, and letters to interested
 parties.  A final review period allows for any additional comments by the public and interested
 government agencies.

 The last step  in the EIS process is the preparation of the ROD; which summarizes the permitting
 action that will be taken, as well as any mitigation measures that will be implemented to make the
 selected alternative environmentally acceptable. (A discussion of the relationship between the NEPA
 review and the permitting procedures is presented later in this chapter.)

 2.2     TRIGGERS FOR NEPA REVIEW ACTIVITIES

 2.2.1    PRIMARY CONDITIONS THAT TRIGGER NEPA REVIEW

 As noted earlier in this chapter, the following two major conditions must be met before NEPA review
 requirements  apply.

 2.2.1.1    New Source Determination

 A proposed NPDES permittee must be determined to be a "new source" before NEPA review
 requirement apply. The determination is made by the EPA Region in accordance with NPDES permit
 regulations under 40.CFR 122.21(1) and 122.29(a) and (b).

 2.2.1.2    EPA is the Permitting Authority

 The second major condition that must be met before NEPA review requirements apply is that EPA is
 the permitting authority. Under NPDES, States and Native American tribes with an approved
 program may administer the permitting program.  In such cases, the proposed issuance of a new
 source permit would not be a Federal action (unless EPA issues a permit in an approved-program
 State pursuant to 40 CFR 123.44(h)). Thus, NEPA requirements would not apply.  As of mid-1994,
 the NPDES permit program is administered in 40 States. In addition to tribal lands, States and other
jurisdictions where EPA is the permitting authority and where NEPA review requirements would
 apply are listed below:
                                            2-7                              September 1994

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, NEPA Requirements and Provisions
• iiiiiiii iiiiiiii ill i n i iiiiiiiiiii . iiiiiiiiii iiiiiiii . ii n i
• Alaska •
* Arizona • •
,'• District of Columbia . •
• • Florida •
• Idaho " •


. '• •»'
1 1 ii i ill iiii i r 1 1 1 ii n i mi i
Louisiana
. Maine -
Massachusetts
New Hampshire
New Mexico

	 	 i 	 , 	 	 	
EIA Guidelines for Mining
i iiiiiiiii y iii|iii iiii in n < i i in i ii MM
• Oklahoma 	
•: 	 :' 	 ' 	 i'" ; 	 	 •' -J 	 	 ^Bk
• Texas ' ^V
• American Samoa
, ' / " 1 ' • •
• Guam
• Puerto Rico
1!
1'
           2.2.2    WHEN is AN EIS REQUIRED?
	:	;	;	;	'	            '	      .         ,  	|	:	
           NEPA requires' that an EIS be prepared for "major" Federal actions "significantly affecting the
<:::=	:' •l=: human	environment."	Generally, the determination of the need for an EIS' hinges on a finding that
'T	'	'	the proposed action would result in rignifiggnt adverse i
iiiJ'IiB i> "iKi1,• >>l:<
                    The new source will induce or accelerate signifigant changes in industrial, commercial,
                    agricultural, or residential land use concentrations or distributions, which have the potential
                    for significant effects. Factors that should influence this determination include the nature
                    and extent of vacant land subject to increased development pressure as a result of the new
                    source, increases in population that may be induced, the nature of land use controls in the
                        ....... and ...... >£Emges'm ..... tie ...... iBvaOabfl^ or 'demand for ewrgy.'. [[[ '
                *  The new source will directly, or through induced development, have significant adverse
                   effects on local air quality, noise levels, floodplains, surface water or groundwater quality
 nil ................................. I ....... or quantity, ...... or fish and wildUfe and their habitats.
                         '     "                         Jl]ii i ..... iiii in in i  iiiiiiiii  i MI i in iii  iiii iiii i ii  in in HSi^fJii ..... t^SSSi'c'/ii'-iS *|i
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 EIA. Guidelines for Mining                                  NEPA Requirements and Provisions

      •   Any part of the new source will have significant adverse efforts on parklands, wetlands,
          wild and scenic rivers, reservoirs or other important water bodies, navigation projects, or
          agricultural lands.

 The determination of significance can be challenging.  CEQ provides some guidance in the form of a
 two-step conceptual framework which involves considering the context for a proposed action and its
 intensity (40 CFR 1508.27).  Context can be considered at several levels, including the region,
 affected interests, and the locality.  Intensity "refers to the severity of the impact." CEQ lists a
 number, of factors to be considered when judging severity, including:

      •   Effects on public health and safety
      •   Unique characteristics of the geographic area
      •   The degree to which effects are likely to be controversial
      •   The degree to which effects are uncertain  or involve unique or uncertain risks
      •   Cumulative effect of the action                                 '                         •
      •   Whether the action would threaten a violation of Federal, State, or local law  or regulation.

In bis review of legal issues associated with NEPA,  Mandelker (1992) summarizes judicial criteria for
significance. He cites the results of Hanfy v. Kleindienst (II), where the court stated four criteria that
could be used to make a significance determination:

      "First, did the agency take a 'hard look' at the problem, as opposed to bald conclusions,
      unaided by preliminary investigation?  Second, did the Agency identify the relevant areas
      of environmental concern?  Third, as to problems studied and identified, does the agency
      make a convincing case that the impact is insignificant? ... If there is an impact of true
      'significance/ has the agency convincingly established that changes hi the project have
      sufficiently FPTi'TTVT'y* it?"

The nature of the mining industry can make it particularly difficult to assess significance.  Potential
impacts are often uncertain, they often are delayed in time from the permitting action, they can be
quite controversial. Several of the more commonly  raised issues surrounding whether the impacts of
a given mining operation could be considered significant are described below.

2.2.2.1    Tmpaets to Already-degraded Environments and Cumulative Impacts

Mining operations -are often proposed in areas where previous mining has occurred, sometimes
directly on sites that have been mined in the past. Many of these areas have been severely impacted
by past mining activity, and the impacts of a modern mine would occur within the context of pre-
existing conditions (it should be'noted that "remining" previously degraded sites can lead to net
improvements in the long-term environmental conditions of a site).  In these cases, there  are three
fundamental approaches for using baseline conditions to evaluate the significance of impacts:
                                              2-9                              September 1994

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                                                                                      I
iinn n linn in n i i n in 11 in in in • i in in i in inn in  M   in i in i  i in ill in 11«« iiiiiii in nini m  in iiinini iiiiiniiiiiii HI inn in       '     ,               -     '    ;           "

              NEPA Requirements and Provisions	EIA Guidelines for Mining
                                                                       	  i     :     	   	   	
                   •  Define natural b&kground conditions as the baseline in assessing significance:  this
             :         approach emphasizes that'additional impacts to already-affected envh-onments are even more
                      serious than to more resilient undisturbed environments.
      *                          '             '                                         i    i
                   *  Define existing conditions as the baseline in assessing significance, but adjust the definition
                      of significance according to the current quality of the resource that would be affected (i.e.;
                      envinfflmentaLefisgg thai would be considered "significant," and thus would trigger an
                      EIS, in an undisturbed natural environment may not be considered  "significant" in one
                      where the resource affected is already degraded, and the degree of degradation also
                      influence? the determination).
                        f                       "	I" I	!	||" ," „!	II	I',"!,	'	,	I	!!,"'""!'!	,' II'T'IIIII	I '",!!""             , I
                      Define existing conditions as baseline but use a consistent definition of "significant.1
            C^Q regulations require descriptions of the affected environment in EI?s (40 CFR 1502. 15) but do
            not address the issue of how or what pre-existing conditions should be taken into account in assessing
            significance.  The courts have : addressed the issue and come to various conclusions.  In practice,
            wasting conditions have assumed a central place both in assessing significance and in considering
            mitigation measures in EAs and EISs.  Environmental effects that would be considered significant in
           • one environment may not be considered significant in another. This has allowed impacts to
            Partially "valuable^ ...... *£ri*S£5S£U^3£S&B&. ...... a ..... significance ...... differently than similar of more
            serious impacts ....... in ...... degraded ..... .environments., .......... TMs ....... jg ...... by no means absolute, however, since the
            assessment of significance is generally mtfc on a case-by-case basis.
           It should be note? that the Glean Water Act provides less flexibility: discharges to waters of the
           United States that do not meet then- State-designated beneficial uses and water quality standards are
           not allowed to further degrade these waters, ibis. has proven to be a problem in some areas where
Ill IIIIIII III II III 111 III
  ••i  i ill i II i n
 4	ill	Sffii-iSS,	        	E£SSbl	*5,SS5;	, A	proposed operation in such areas could
 "threaten a violatign p||gderal. State, or local law or requirements imposed for the protection of the
 Cmdr0nmenr(t£	EH	ME:E*X!°1	***,***	HSM	tei'iSSrfor	fflsldjaation	|n deterrnining
 *t SSSS	££l!S	SS2SI	2222:	IMS	is P9»nts out the need for sufficient technical
 documentation of the basis for determination of how a project will ensure compliance with applicable
 water quality standards.        -
                                                                         i  n

In addition, CEQ regulations include "cumulative"  impacts among the environmental impacts that
must be assessed under NEPA,	CEQ defines (40 CFR 1508.7) cumulative impacts as "the
                  51SfJk?.?^00. Ffeen added to, other past, present, and reasonably foreseeable
           future actions...^ This is important _fpr proposed, mining operations for two reasons,  First, new
           mines are often located in areas-or directly on sites-where mining took place in the past, and where
           there are residual impacts from that mining.  As noted above, this can complicate the process of
           ,*??%£% frS±S .....           .......         ....... JS ...... gSSffiSfe,expensive.  Second, metal mining operations
           m particular almost ..... invariably ...... evolve ..... and expand during ^their active lives, ................ The,,,nature,,,,and,,,extent of

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 EIA Guidelines for Mining	      NEPA Requirements and Provisions

 future operations depends on the experience gained with the initial operation and on information that
 is not .obtained until operations begin.

 For example, the sizes of and gold concentrations in ore bodies are never fully understood until the
 ore body is mined, so the ultimate success in recovering the gold, and the ultimate extent of mining,
 are simply not known at the time initial environmental evaluations must be conducted. Typically,
 facility design and operations evolve as more and better, information is gained during mining
 operations, and the evolution is captured in proposals for major expansions.  Such proposed major
 expansions usually trigger new evaluations of potential and actual environmental impacts. These
 evaluations are limited by similar information gaps at the time the evaluations are made.  However,
 there is always much more detailed site-specific information (both environmental  and operational) at
 the time of a planned expansion, since these types of information are gained during operations. This
 information could be used to assess the adequacy of the initial environmental evaluation,  and thus to
 guide the evaluation for the expansion, but this is not always the case. Indeed, it is not uncommon
 for secondary environmental evaluations to be confined to incremental effects of the expansion, not to
 the total impacts of the evolving operation.  Thus, assessments of potential environmental impacts of
 expanding operations may sometimes be less comprehensive even than initial evaluations. In
 assessing impacts under NEPA, however, CEQ regulations make it clear that an environmental
 assessment or EIS consider the sum total of impacts (i.e., the cumulative impacts).

 2.2.2.2    Uncertain Tmpartc

 As noted above, CEQ regulations (40 CFR 1508.27) indicate that assessing significance requires
 considerations of "context" and "intensity."  Intensity, in turn; "refers to the severity of  impacts,"
 and the regulations list a number of factors that should be considered hi evaluating intensity. These
 include consideration of "the degree to which the possible impacts . . . are highly uncertain or
 involve unique or. unknown risks" (§1508.27(b)(6)). Uncertainty regarding both immediate and
ultimate impacts is a characteristic of most mining operations, particularly metal mining.

In some cases, there may be a relatively low (but to some extent quantifiable) probability  that a
mining operation will cause a significant environmental effect, but the effect, were it  to occur,  could
be severe.  Whether such risks "require an impact statement has'received surprisingly little attention"
by the courts (Mandelker, 1992). Mandelker cited one case that addressed the issue,  hi which it was
found that effects which were "only a possibility" could indeed be considered in an impact statement,
and that the agency would have "some latitude" hi making a determination that an EIS was or was not
necessary ((Conservation Law Foundation v. Air Force, 26 Env. Rep. Cas. 2146 (D.  Mass. 1987)).

This can be an important issue hi the  case of mining.  Acid generation potential, and  the development
of acid drainage, for example, can be extremely difficult to predict. There are some  mines where
acid generation can be predicted with  some, confidence, and others where there is only a remote or no
                                            2-11                              September 1994

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             NEPA Requirements and Provisions	^^ Guidelines for Mining
	chance of acMjeneration.  For many perhaps most) mines, however, i,tfaere_|s, substantial uncertainty
	  as jto ii'i5tin^,,Qcsurrence,i as described in Chapter 4. Often, acid generation is considered unlikely
             fail possible, or likely but not .certain, based on information available at the time. Other active and
             abandoned mines in a particular area may give some idea of the possibility or probability that acid
             generation will occur, and any such information should always be assessed. Uncertainty regarding
             future acid generation is very common at the time of mine permitting (or approval).  As the geology
            ^ geocjiemjstry Q| jjjg ore b_dy ajyj of waste materials are better understood .during the life of the
            nime, more accurate predictions can be made; periodic testing and prediction are sometimes required
            throughout the life of a mine by States, or Federal regulators.  There are some cases, however, where
            substantial uncertainty exists even at mine closure/reclamation.

            When acid drainage' develops, it can have catastrophic effects on water quality and aquatic resources
            in particular environments.  It is nearly always possible to assess the potential impacts on water
    t _..„!!!,..,_ quality should acid drainage occur, using various reasonable (and/or worst case) assumptions as to
            flow rates and frequency, pH, metals concentrations, etc.  This information could be used together   '
            with information on existing surface water or groundwater quality and on aquatic resources, to assess
            the significance of acid drainage should it develop. The assessment of acid generation potential (in
            terms of its probability) cou_& then provide guidance as to whether an EIS should be prepared for new
            source permit issuance (or for other agencies' actions that authorize development of a mine).

            When potential impacts could have catastrophic consequences, even if the probability of occurrence is


            casds. These regulations apply to situations where an'EIS is being prepared.  In general, the
            regulations require that incomplete or unavailable information be obtained and included in the EIS
            unless toe cost would be "exorbitant."  When costs would be "exorbitant," the EIS must include a
            statement that the information is incomplete or unavailable, a statement describing the relevance of the
            information to the evaluation, a summary of relevant credible evidence, and the agency's evaluation
            of potential impacts based on "ti^retical approaches of research methods generally accepted hi the
            ^aenjific community."  Any such analyses must be "supported by credible scientific evidence," must
           not be "based on pure conjecture," and must be "within the rule of reason."
           2-2.23    Delayed Impacts
                  . JSP*?*' as" defined by CEQ regulations (§1508.8(b)), include those "caused by the action and
           later in time or farther removed in distance, but still reasonably foreseeable.''  Such -impacts must be
                     ..... HLffi ..... ££», snd significant delayed impacts can trigger an EIS. An example of a delayed
                    the context of mining wouy jjg acid drataage whose onset occurs years or decades after the
           mine opens (or closes). However, there must be a causal relationship between the Federal action (hi
           this case, permit issuance or other approval) and the indirect effect: the action must be "proximately
                                                       2-12                              September 1994

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 ELA Guidelines for Mining                         .        NEPA Requirements and Provisions

 related to a change in the physical environment" (Metropolitan Edison v. People Against Nuclear
 Energy, 460 U.S.  7866 (1983)). This would be the case in the case of a new source permit (or other
 approval), since the changes in the earth's surface in excavating a pit or an underground mine, or the
 placement of materials in a location and in a configuration that can lead to acid drainage, would be
 the direct result of issuing the permit (or approving the plan) and thus  allowing me operation to go
 forward.  For at least some mines, however, it is not clear if acid generation is "reasonably
 foreseeable," since mere can be substantial uncertainty as to its ultimate development.  Any prediction
 of acid drainage would seem to have to be quantifiable (or otherwise supportable) to some extent,
 since at least one court has determined that "unquantified speculation"  (American Public Transit
Association v. Goldschmidt 485 F. Supp. 811 (D.D.C. 1980)) that subsequent events would occur is
not sufficient to qualify an action as significant.

2.2.2.4    Duration of Impacts  .

In general, temporary impacts are not considered significant, but generally the operations of all but
the most ephemeral placer or coal mines would not be considered temporary. Specific activities
associated with mine development, operation, and closure/reclamation are indeed temporary (e.g.,
construction activities associated with mine development), but would have to be considered in terms
of the cumulative impacts of all the effects that result from the Federal action.

2.2.2.5    Transfer of Responsibility for Facility
                                                                                         i
The possession of (or responsibility for)  a mining facility can change hands several times over the
active life of the faculty. In some cases, EPA (or another agency) may have reason to believe that
the new responsible party (i.e., the new permittee) will be less able or less willing to carry through
on commitments made by the previous parry.  For example, the site, and the responsibility for
implementing mitigation measures, can become the responsibility of an owner or operator with less
experience in dealing with issues faced by the mine, smaller in size and/or financial resources, with a
worse history of environmental performance, and/or with differences in other regards that give rise to
the concern.  The transfer itself would not be a "major Federal action" (certainly, it would not
involve issuance of a new source permit  unless site conditions/operations changed). It is not clear if a
transfer accompanied by material changes in stipulated mitigation measures (e.g., a change in the type
or amount of bonding required by a State or Federal agency) would allow for any intervention by
EPA, even though  this could have major environmental  implications.

2.2.2.6    Controversial Actions and Impacts

CEQ  regulations (40 CFR Part 1508.27(b)(4)) provide that agencies are to consider whether
environmental effects are "likely to be highly controversial" in assessing their significance, and thus
determining whether an EIS must be prepared.  Mandelker cites the leading case that addresses this
issue, Hanfy v. Kleindienst (H) (471 F.2d 823 (2d Cir. 1972)): "the term 'controversial' apparently


                                             2-13                              September 1994

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          NEPA Requirements and Provisions _ _ .     _     EIA Guidelines for Mining
                                                                                  i

          refers to cases where a substantial dispute exists as to the size, nature or effect of the major federal
          action," not to "neighborhood opposition."  Many or most proposed mining operations are subject to
                                                                          [ *?. ,!!?• ' H°w?vels,, for many
                              £2,15, ..... SSSHSS ..... 52SS££ ...... SS ...... 2SSSS? ^nceminty-rjBgmi^gto "size,
          nature' ...... of ...... (£&&" of tte-poteffijal imoacts; or aU^ three.  This uncertainty can be particularly i acute as to
          die ultimate extent of the operation (this occurs at many metal mines, since the full extent of the ore
          body is seldom known at the time the mine begins operation) and to the potential impacts of a given
          operation (given the uncertain extent of the operation in the case of metal mines and the difficulty in
          predicting the course of reclamation and ultimate performance of mitigation in the case of both metal
       	and coal mines).         .             ,         _..-..

         2.2.3    THE RELATIONSHIP BETWEEN NEPA REVIEW AND NPDES PERMITTING ACTIVITIES

         How the NEPA review, process affects NPDES permitting activities is a complex issue.  EPA
	i	regulations clearly establish procedural and timing relationships between the two processes.'
         However, how the findings of a NEPA review can affect me substantive omrame of me
         process" 1 less	555!	fapa^culai;	j^ere	g	a'gn^'area	as	to	how	Ep^llllpjoujj|	JJStosTNEPA	'	"	
         review findings that are not related to water quality.  As summarized by Mandelker (1992), in a
      '  recent court base it was held that NEPA  does not confer on EPA the authority to impose conditions in
         effluent discharge permits that are not related to water quality or to'other areas within the purview of
         the Clean Water Act.1 However, die court held that NEPA authorized EPA to  impose NEPA-
         inspired water-related conditions on permits for effluent discharges and to rely on jggp^ to ^eny a
         discharge permit.  Thus, for example, if a NEPA review indicated that construction associated with a
         proposed new source discharge would adversely affect a significant historic resource, EPA would not
         be authorized to include in the NPDES permit any conditions that related to that construction.
         However, EPA would be authorized to deny issuance of die permit'based on a finding that was not
         strictly related to water quality.   .

       * It should be noted tiiat most States in which mining occurs have assumed responsibility for
iiiiiii i (iiiiiii  IP in adrnmistering die NPDES program.  Consequently, EPA now issues very few NPDES permits to
         mining operations  (new  sources-or otherwise) and thus is not responsible for NEPA compliance: for
         such permit issuance very often (neither State issuance of new source NPDES permits, nor EPA's
         concurrence in such issuance, triggers NEPA).	However, other Federal agencies are frequently
         responsible for preparing EAs or EISs on new mines.  Mining often occurs on Federal lands hi die
         west, tims requiring NEPA compliance by die Bureau of Land Management, Forest Service, or other
2	"i  !	"land management agency. Also, new mines often	require issuance of a Clean Water Act §404 permit,
         thus requiring NEPA compliance by die Army Corps of Engineers.  When an EIS is prepared in such
         cases, EPA often participates as a cooperating agency in the NEPA process pursuant to 40 CFR Part
            'Natural Resources Defense Council, Inc. v. Environmental Protection Agency, 859 F.2d 156 (D.C. Cir. 1988)
  mil i i  II 111  inn i iiiiiiiiiiiiiiiiiiini iiiiiiiiiiiiini limn n n inn iiiiiii ill i inn iiiiiii iiiii i i iiiii nil n iiiiiii inn i in n i nun iiiiini niiiiiiiin i i • hi i i t'l .TIS'IIIIUIIF; .:.n, iii,i:: Jin;*:1:	!	i	 	»:	m
                             •1 1 IIIII 11 11 1 I III III 1111111
                                                    2-14                             September 1994

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EIA Guidelines for Mining    	     "	NEPA Requirements and ProTisions

1501.7.  Even where EPA does issue a new source permit, another Federal agency may be the lead
agency in preparing the EIS, again with EPA participating as a cooperating agency.

23    LEVELS  OF REVIEW

Environmental analysis under NEPA is a process that is attended by extensive internal, interagency,
and public review. In particular, NEPA involves a>strong mandate to involve the public hi the
environmental analysis process.  As discussed below, document review is an element of all major
aspects of the analysis process. The formality and intensity of review increases with each escalation
in the hierarchy of NEPA documentation.  So, EIDs are subject to the least formal  and extensive
review; while EISs are subject to the greatest level of review.

2.3.1    ENVIRONMENTAL INFORMATION DOCUMENT (EID)

The EID, which is prepared by the permit applicant, is reviewed by the EPA Region: Although no
formal public notice is involved at this stage, documents prepared as part of the NEPA review process
are intended to be readily available for public review.  The applicant may request confidential
treatment of certain types of business information that is provided as part of the EID.

23.2    ENVIRONMENTAL ASSESSMENT DOCUMENTS (EA)

The EA,  which is prepared by EPA Regional office staff (or by contractors or the permit applicant
under EPA's auspices), is reviewed and approved by the EPA Regional Administrator or designee.
The Regional Administrator is formally the "responsible official" for EPA's action.

The Regional Administrator is required to give notice and make EAs and FNSIs available for public
inspection.  EAs and FNSIs are reviewed by staff responsible for making permitting decisions prior to
those decisions. Copies of EAs and FNSIs are included in the official administrative record for those
permitting actions.

2.3.3    ENVIRONMENTAL IMPACT STATEMENTS (EISs)

Notices, determinations and other reports and documentation related to an EIS are reviewed internally
by EPA to the level of the Regional Administrator, who serves as the  "responsible official," or the
Regional  Administrator's designee.  Through consultation processes with cooperating and other
interested agencies, EPA provides opportunities for joint decision making and review. These
consultation activities take place throughout the EIS preparation process, beginning  with initial
discussions regarding the determination of the appropriate Federal lead agencies through review and
comment on the (EIS) ROD.
                                            2-15                             September 1994

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              NEPA Requirements and Provisions _ '           _ EIA Guidelines for Mining

                               i
              The public, too. is provided many opportunities for review and participation in the assessment
              process.  These opportunities include the following:
                         ^  II i I      ,            PI            9

                   •   Publication of the NOI in the Federal Register provides an opportunity for parties to express
                       their interest in an EIS action.

                   *   A scoping meeting is held early in the process to solicit public and government agency
                       advice on the issues mat should be addressed and any relevant information that should be
                       considered in the assessment process.

                   *   Draft EEJS are made available for review by the public and interested government agencies.
                       Cooperating and interested parties are provided review copies of Draft EISs.  Other copies
                       are provided in easily accessible areas, such as public libraries in the local area of the
                      proposed action.  EPA must respond formally to all comments made on the Draft EIS.
                      Comments and responses are represented in a special section of the final EIS.

                  *   Similar notice is provided of the availability of Final EISs and RODs and copies are sent to
         [[[ interested;parties for their review.

                  *   The Office of Federal Activities (OFA) also maintains copies of EISs for public review and
                      also provides a copy to CEQ for its review and consideration.
                                         «
            Draft fi1131 EISs and RODs are subject to internal review at the regional level, prior to release.
            Coordination of the internal review is by the lead branch among the regional program branches:
            Depending upon the nature of the specific issue, EPA's Office of General Counsel (OGC), OFA, the
            Office of the Administrator, or other EPA offices may also be included in the internal review cycle.
                                                                          i   1 1  i      i  *  .................
                                      Hi nil 11111 HI ill
            As is noted elsewhere, EPA's authorization of most States to administer the NPDES system has
            resulted in only occasional issuance by EPA of new source NPDES permits for mining operations.
            Even then» EPA Regions more often act as a cooperating or oversight agency on EISs prepared by
            o^1" federal agencies (e.g., Federal land managers or the Army Corps of Engineers).  In these case,
           	EPA revi^	pteliminai3r;dia?s,,,, aiKi ,othe£	ElS-related^ *»™??:	The junsfflctional	and,, other	
            reaspilsyfdr determining lead vs. cooperating agency roles are discussed in CEQ regulations at 40
            CF^ J3* ISO1; Vfte^O*?. Circ^mstan5es' me EPA Region typically drafts a memorandum of
            agreement (MOA) with the lead rapd agency, defining respective roles.  EPA participates to
            va*3[ingIevds m me preparation of the EIS document (with the objective of adopting the EIS), and
I|ii^        issues,^ EPA ROD. As would be the case if EPA were the lead agency,  the EIS is part of the
            administrative, record for the NPDES permit and should be complete with regard to documenting the
            basis for the decision to issue the permit.
                                                        2-16                             September 1994



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 EIA Guidelines for Mining	_	     NEPA Requirements and Provisions

 2.4    INFORMATION REQUIRED FROM PERMIT APPLICANTS

 In :^c6rdance with EPA NEPA procedures, the nature and extent of information required from
 applicants as part of the EID are bounded by two separate requirements:

      •  EIDs must be of sufficient scope to enable EPA to prepare its environmental assessment.

      •  In determining the scope of the EID, EPA must consider the size of the new source and the
         extent to which the Applicant is capable of providing the required information. EPA must
         not require the Applicant to gather data or perform analyses which unnecessarily duplicate
         either existing data or the results of existing analyses available to EPA.  EPA must keep
         requests for data to the minimum consistent with the Agency's responsibilities under NEPA.

 The EPA procedures call for EPA to consult with the applicant to determine the scope of the EID at
 the outset of the process. As discussed hi more detail in Chapter 5 of these guidelines, elements of
 the EID will be consistent with general requirements for the contents of NEPA documents.

 Among the types of information required for EIDs is a balanced description of each alternative
 considered by the applicant.  These discussions should include the size and location of facilities, land
 requirements, operation and  maintenance facilities, waste management units, auxiliary structures such
 as pipelines or transmission lines, and construction schedules. ,

2.5    TIME INVOLVED  IN PREPARING AND PROCESSING NEPA DOCUMENTS

 The time required to complete NEPA documentation requirements will vary considerably depending
upon the complexity of issues, public controversy, and other factors. As shown on Exhibit 2-2,
completion of the EA process generally requires at least 5 to 6 months; while  completion of the EIS
process ideally requires between 12 to 20 months but usually takes somewhat  longer.  As noted on
this exhibit, some elements of the schedule (e.g., public review periods) are established by regulation,
while others are more flexible.

Under EPA's NEPA procedures, the Applicant may request that EPA establish time limits for the
environmental review process consistent with 40 CFR 1501.8.

2.6    LIMITATIONS ON PERMIT APPLICANT ACTIONS DURING THE REVIEW
       PROCESS

EPA NEPA procedures state that actions undertaken by the applicant or EPA shall be "performed
consistent with the requirements" of 40 CFR 122.29(c) (see amendment in 51  FR 32609, September
 12, 1986). In his treatise on NEPA law. and litigation, Mandelker (1992) cites a key case that bears
on this issue.  In Natural Resources Defense Council, Inc. v. EPA the court held that, provided no
discharge occurred, EPA could not prohibit construction of a new source.
                                           2-17                       .     September

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               NEPA Requirements and Provisions
                                                                                       EIA Guidelines for Mining
                                   iiiiii i i in i  iiiiiiiii  illi 11 ill iniin iiiiii in iiiiiiiiiiii  inn
                                                                              Jill IIIIIIII  111 111 III 111 III Illlllllllllll I  111 IIIIIIIIIIII 111 111 IIII IIIIII III IIIIII III IIIIII  IIIIII Illlllllli  III  IIIIIIIIIIII  IIIIIIIIIIII III I 111 111 111 IIIIII
       «:	'li
         ^^
IIIIH^^^^^	illi

                     Exhibit 2-2.  Model Schedules for EAs and EISs for Proposed Issuance of New Source
                                                           NPDES Permits
                        Determination of N«w
                        Sourc*/EPA»
                        permitting authority
                                                       Appfcant prepare* and submits EID (1 month)
                                                       EPApreparation of Draft FNSt internal rwriaw;
                                                       public notie* (1 month)
                                                                             '
                       Action detemftMd to
                 •ignfficant advene
                 impacts and action
                 cannot be modified to
                 be environmentally
                                                          Environmental Assessment (EA)
                                                                  l Impact Statement (EIS)
                                                      Drafting of NOI; inttrnal ravimr; pubfication and
                                                      e5st«nm*tkx)toint«r»st«dp«rtiM(1 month)
                                                      Pntparationot dfaft BS; internal ravimM
                                                         6 month*)
                                                                                                   p*riodof4S
                                                                                                   day*
                                                      i*«iaaaa«Bi)j8!3eiiaaaaBi
                                                              o cemrnwits. prtparafion of final BS:
                                                     «a«mal ravimr and osuancc (2 - 4 months).
                                                          eiwvtorpviodof
                                                     tewie* of RCX) and doMmtnation to pattws %«ho
                                                     comnMntwi on draft or fhal EISs (1-2 months).




lil'lilr;	lHK:tfV VMnh&W^'SHilYlEfll
                                              '
                                                           2-18
                                                                                                                                         ..... I
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EIA. Guidelines for Mining  .         	Overview of Mining and Beneficiation


               3.  OVERVIEW OF MINING AND BENEFICIATION


This chapter presents an overview of the processes and activities associated with metal ore and coal
mining and beneficiation as currently practiced in the United States.  The activities and processes for
mining and beneficiatirig many metal ores are quite similar in many regards, so the first sections (3.1
and 3.2) describe general concepts of ore mining and ore beneficiation which apply to one or more of
the commodity sectors.  These general overviews are followed by commodity-specific profiles
(Section 3.3), which discuss in greater detail those aspects of mining and beneficiation that are
particularly important within each of the commodity sectors. These profiles emphasize the process
variations that are unique to mat ore, the chemical reagents typically used in beneficiation of each
ore,  and physical/chemical properties that result in the discharge of unique waste streams.  Coal
mining and coal processing are then addressed in individual sections (3.4 and 3.5).

3.1    ORE MINING

Mining activities generally consist of exploration, site development, ore extraction (including drilling
and blasting, surface mining,  and underground mining), and restoration/reclamation.  Processes
typical of these activities are discussed below.

In developing effluent limitation guidelines for discharges from mines, a mine was defined by EPA
(1982) as an area of land upon or under which minerals or metal ores are extracted from natural
deposits  hi the earth by any means or methods.  The mine includes the total area upon which such
activities occur or where such activities disturb the natural land surface.  A mine also includes land
affected by ancillary operations that disturb the natural land surface, and can include any adjacent
land the use of which is incidental to any such activities; all lands affected by the construction of new
roads or the improvement or use of existing roads to gain access to the site of such activities; all
lands associated with haulage and excavations, workings, impoundments, dams, ventilation shafts,   •
drainage tunnels,  entryways, refuse banks, dumps, stockpiles, overburden piles, spoil banks, tailings,
holes or  depressions; and all repair areas, storage areas, and other areas upon which are sited
structures, facilities, or other property or materials resulting from or incident to such activities.

Similarly, hi developing effluent limits for discharges from mills, a mill was defined by EPA (1982)
as a preparation facility within which the mineral or metal ore is beneficiated by being cleaned,
concentrated or otherwise processed prior to shipping to the consumer, refiner, smelter or
manufacturer who will extract or otherwise use the metal contained in the ore.  This ore preparation
includes .such operations as crushing, grinding, washing, drying, sintering, briquetting, pelletizing,
nodulizing, leaching, and concentrating by gravity separation, magnetic separation, flotation or other
means. A mill includes all ancillary operations and structures necessary for the cleaning and
concentrating of the mineral or metal ore, such as ore and gangue storage areas and loading facilities.
                                                                               September 1994

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            Pro-view of Mining and Benefication	•      	EIA Guidelines for Mining

           	:	:	:	,	:	:	!	;:	L;	:	;	:	i	
            3.1.1   EXPLORATION
           In the ore mining industry, exploration is defined as all activities and evaluations performed to locate
           and define mineral deposits for the purpose of extraction now or in the future.  Exploration activities
           range from efforts of a one-man prospector to use of sophisticated ground and airborne sensing
           equipment, and extensive sampling and testing programs.  A typical exploration program consists of
           four principal stages (Bureau of Mines, 1977):
 llllllNiH I 111 ill1  Hill     I 11111 III Hill!      '      II  Hill  lilllllllllll Illllli 111 111 i ill 111 Hill Hi III II  111 111 II I
                                 _
                 *   Regional 'appraisal
                 •<   Dete^ed reconnaissance of favorable.areas
                 •   Detailed surface appraisal of target areas
                 •   Detailed sampling and analysis.
           A regional appraisal (Stage 1) typically consists of a review of aerial photographs, geologic maps,
           geophysical maps, published reports, and other available literature and may cover an area from 2,600
           to more than 260,000 square kilometers (km) (1,000 to 100,000 square miles).  The detailed
           reconnaissance of favorable areas (Stage 2) typically covers 26 to 260 km (10 to 100 square miles),
           and involves more extensive geologic aid geophysical surveys using techniques such as geologic
        '   mapping; stream, sediment, and rock sampling; and non-destructive ground and airborne magnetic,
           electromagnetic, radiometric, and remote-sensing imagery studies (Bureau of Mines, 1977a). Stage 3,
           the detailed appraisal of target areas, may involve all of the non-destructive evaluation methods used
           in Stage 2, and often includes destructive sampling efforts such as drilling and the excavation of test
          pits and trenches. These target area examinations usually cover from 3 to 130 km (1 to SO square
          miles), and may identify the existence of mineral deposits that constitute potential ore bodies.  If
          further definition of the potential ore appears warranted, then  a three-dimensional sampling and
          preliminary evaluation program (Stage 4) will be conducted. A Stage 4. investigation typically covers
          from 1 to 25 km (0.4 to 10 square miles). Its purpose is to identify the study boundary or limits, as
          well as the depth, size, shape, mineralization, and grade of the potential ore deposit. Testing
          activities may involve extensive drilling; excavation of test pits^  trenches, shafts, and adits;
          ^™^_^_ ___^_ ^_^ _^__^ __^ ^ maj^ Q~er forms of destructive testing, as well as the
	,	rwtHje&nictive	techniques	already	described.	Tjre extent	of these	tests	will	depend greatly upon the
          location, accessibility, geologic setting, and types of minerals  under investigation.  In addition,
          support activities such as the construction of access roads and  the building of temporary living
          quarters may be  undertaken!
  •                                  " '                          .               '.     ,   • i
          The first two principal stages include very limited destructive testing,  if any. The potential for
          adverse environmental impact is thus limited to those impacts associated with gaining access to the
          areas.  The last two stages, however, involve destructive testing  activities which may be undertaken
          before  or after permit applications are filed.  Therefore, construction activities and destructive
                               " : -             ,                              .  "	I      •]
          exploratory testing that may result in adverse environmental impacts can occur prior to the filing of
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                                                                                                                 ,' iilETi'i,,  ,,1'ilLill I'"?"!!!!
                                                       3-2                               September 1994
          111	lilllll	!•                       	IIM^^^                	lllillliilllliM	Iliillli

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 EIA Guidelines for Mining                               Overview of Mining and Beneficiation

 applications for NPDES, PSD, and other Federal, State, and local permits. The exploratory tasks
 conducted by the permit applicant, and the known environmental impacts (adverse and beneficial)
 resulting from the exploratory activities, should be well documented within the BED.

 3.1.2    SITE DEVELOPMENT

 Once a mineral deposit of commercial value has been defined by exploration activities, it is necessary
 to construct facilities for extracting the ore, beneficiating it if necessary, and transporting it to market.
 The site development process has many possible stages depending on the type of mine projected and.
 its relation to the surrounding transportation system.  Site development activities may include the
 following.

 3.1.2.1     Construction of Access Roads, Rail Lines, or Ship/Barge Terminals

 Road and rail lines will require clearing a right-of-way, filling or excavating to a desired grade, and
 paving or laying rail. This may involve the use of earthmoving equipment such as graders, scrapers,
 bulldozers, power shovels or backhoes.  These operations may result -in the destruction of vegetation
 along die right-of-way, and possibly the production of excess earth from excavation or the
 requirement that borrow pits be created for obtaining fill material. Overburden or waste rock from
 the developing mine may be used in road or other construction.  In a few cases, acid-generating waste
 rock used for various purposes has caused significant problems.  In previously undeveloped terrain,
 the removal of vegetation and/or soil cover may cause an increase in the rate of local erosion, and,
 where terrain is steep, increase the potential for mass wasting processes such as slumps, landslides,
 and mud flows.  If excavation extends into hard materials, blasting may be employed.  It can be
 expected that these operations will produce brush and timber debris which must be removed, buried,
 or burned if permitted.  There will also be dust generated during earthmoving.  Development of ship/
 barge loading facilities may require dredging and construction activities that disturb bottom sediment.

3.1.2.2    Construction of Mining Facilities

Initial work at most mines involves obtaining access to the ore bodies. At surface mines, topsoil and
overlying rock must be removed; at underground mines, shafts, or adits must be driven. These
operations involve the operation of earth moving and construction equipment, the erection of
structures, and, possibly, major excavation. Waste rock dumps must be provided and topsoil may be
stockpiled for future use in restoration activities.

Also, ancillary facilities such as maintenance and office buildings may be constructed during this
stage.  At many larger mining operations, living facilities for mine personnel may involve the
construction of major housing, shopping, and recreational developments.
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Ill 111 Illllll
  Overview of Mining and Benefication	EIA Guidelines for Mining

 3.1.2.3    Construction of Mfll Facilities                     -
                                      1	'"'	'	''''	'	"	'	!	'!''	''	'n''	''	"'	|!	'h	!'	'	!	I1"1	'	l|1'""	'" ""'4|	*'"'	"'	"'	!"'
 Unless the ore is of such a high grade that it can be economically shipped for offsite beneficiation, a
 mill must be constructed in order to beneficiate the ore to a marketable grade.  Usually the mill will
 be located as close to the mine as is practicable in order to reduce the costs of transporting the raw
 ore. However, in some.cases, conditions dictate construction of a mill at a considerable distance
 from the mine and sites at lower elevation are always preferred.  Roads, railway lines, and/or
 conveyors must be constructed	train the	'mine'	to^'mOL	The	^^	——	—- ——-—^-.~	
 generally be similar,to those incurred in the construction of any industrial/nianufacruring facility.
 Land most be cleared of vegetation	and preparey	excavation	and grading.  Materials must be   ''
 transported to the site and assembledby a sizeable labor force. These operations may result hi the
 production of vegetation  and construction debris, emission of fugitive dust,  generation of noise from
 construction machinery, and increased sediment loading to local  streams, as -well as secondary effects
 caused by the influx of construction laborers.

3.1.2.4    Other Pre-Mining Activities
            Other aspects of mine/mill development may include the need for installing utilities (i.e., electrical
          „ ^f°222S£S	SB,	°£	ESS	lies) to toe she, or hi remote areas constructing a power plant and/or
            ^^^ &*PPty system. In very remote regions, it may even be necessary to construct a settlement
            G-e-» tiring Spacers jnd support facilities) for the mill construction and operation personnel.

           3.1.3
           Minerals are extracted from the earth by a wide variety of techniques.  In general, inining consists of
           removing the ore from the host rock.or matrix and transporting it away from the mined site: In the
           interests of economic efficiency, the extraction process is designed to remove ore of a predetermined
 "~ZZ! ...... &?$*. ..... °1 ..... ^?E» ...... !e§Y5S behind lower-grade ore and barren rock if this is, practicable.  In practice,
 ™5?':±5^^?. ...... ^5 ...... 3S!— 2 ..... SEt^3^ Possible, so that 'some lower-grade rock is mined and some
 fSSiSlSlSJSSSS: ZSrJf- ^^: ............... 1^?. ...... ***!, ..... ?*te JfS ..... ^fffi^Oft-IPfflea ..... 5S§t8 ...... SBk, "subore, " and ore
           fe an economic one that varies from mine to mine and can vary in time at specific mines.) Most
 SS^Si5;i:i^??i!fe^.,ff2S?S2 ...... 5=5!! ....... "~ ..... ^I^lSl,0! ,§??„ ..... and, associated rock or matrix in bulk form from the
                   "*"* various mechanical means to break the ore into pieces of manageable size or to separate
              ore minerals from unwanted material.
              1 1 Illllll III 1 11 1 III III ill I III I Illllll II III I III Illllll IIIIIIH  III III 111 Illllll III II I I III II  I III I III III   II Illllll   III   I Illllll I  II I    I III I III Ml 11 Illllll III III III 1 1 III I  III III ' III  II I   1 1 III    I II 1 1 II I      I    I IllllhUlllllife  ..... !"'> ..... l.'t
              	SL!!^!11!!!"68,	JElHf?6,,	*?„	HSS	°I,e?plosives or heavy machhiery to break up or to excavate
              ore-bearing rock or matrix; high-pressure streams or jets of water, to disaggregate beds of
                  :; sluices, riffles and other hydraulic devices to separate placer minerals from the bedload of
          streams.  Some (copper and uranium) ore deposits are suitable for extraction by in situ solution
          techniques, in which the ore minerals are dissolved hi the ore body by solvents and pumped to
          processing' areas in solution.
                                                        3-4                              September 1994
                                                       i 11 ill in 111 PI i  in in  i  i i i  i ill in n iiiii in iniii1111 mi ni in   nlii11     in  nun iiiiiiiiiiiiiiiliiiiiiiiiiii ill i n  11 nil

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 EIA. Guidelines for Mining	'.   Overview of Mining and BeneStiation

 Although mining processes may be classified according to the numerous techniques that are employed
 in removing ore, they can be broken down into two broad categories that are associated with the
 general setting of the running operation.  These are:  (1) surface mining or open-pit processes; and
 (2) underground mining processes. Specific techniques and applications within this framework are
 discussed below.

 3.13.1    Surf ace Mining

 Surface mining is the major type of mining operation for most of the major metallic ores in the
 United States.  This is the method of choice when the ore deposit is near the surface, or is of
 sufficient size to justify removing overburden.  At present, this is the most economical way of mining
 highly disseminated (lower-grade) ores. Generally, ore deposits must be within 150 meters
 (approximately 500 feet) of the surface for surface mining methods to be economically feasible.
 Surface mining methods typically used for ore extraction are discussed in the following paragraphs.

 3.1.3.2    Open Pit Mining

 This method involves excavation of an area of ground and removal  of the ore exposed in the resulting
 pit. Depending on the thickness of the ore body,  it may be removed as a single vertical interval or in
 successive intervals or benches.  If the ore is mined as a single vertical interval, it may be feasible to
 place waste rock from one area in the space (pit) left by previous mining of the adjacent area.   ..
 However, the ore body generally is mined in benches after the overburden has been completely
 removed from.the mine area.  In resistant materials, the procedure usually employed involves mining
 each bench by drilling vertical shot holes from the top of the bench, and then blasting the ore onto the
 adjacent lower level.  The broken ore and  waste rock then is loaded into rail cars or trucks for
 transport to the mill or waste rock dumps, as the case may be. In less resistant materials, the ore
 may be excavated by scrapers or digging machinery without the use of explosives. A variation of
 open pit mining involves use of a central shaft (or glory hole) into which ore from an open pit is
 dropped. The ore is allowed to move downward through the vertical or inclined shaft to an
 underground level where it is loaded into cars for  transport to the surface. This method is especially
 favored if the ore body is relatively deep and narrow.

3.133     Dredging

Placer deposits are concentrations of heavy metallic minerals which occur in sedimentary deposits
associated with watercourses or beaches (either current or ancient).  These deposits can be mined by
surface open pit methods, but in some cases can be better handled by dredging. For this method, the
mine area is flooded and the excavating/mining equipment mounted  on a barge. In hard materials the
dredge uses a mechanical digging system to break  up and excavate the deposit, while soft deposits can
be removed by hydraulic suction alone.  Mechanical dredges  can use individual digging buckets
(clamshells) to excavate the material; or, if conditions permit, will use a chain of buckets which dig


                                             3-5                              September 1994

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             Orei-view of Mining and Benefidation
	:	I	:	;	:	
         I!
   EIA Guidelines for Mining
             85 ^ continuoussequence and transport material steadily into the dredge for processing.  Suction
             dredges essentially operate as "vacuum' cleaners" to mine out the alluvial material, although some
             ***&* E!°!E1<:?&£ te?dB.5Minbreaking up the material prior to its removal by suction.  Placer
             deposits can also be worked with small portable suction units and by traditional hand sluicing and
            panning; however, these portable suction and panning methods can handle only limited volumes of
            material.  There are no commercial dredges operating in the United States as of jhe11990s, although
            ,$f ffffaofogy may be in use elsewhere.  Also, suction dredging hi the United States is mainly
            practiced by recreational miners or very small commercial miners
                             *   i          	      _                                  i  .
                «             •                         -       i      i         i       ,  PI  ,
                                                                                      ii
            3.13.4     Underground Mining
  ill in i1 i iiiiiiiiiin	i II • 11 n
                    k                          	 L   	        .  •   ,M • ',     	,»,   • . ,  ', .. t -i • • •    	   '   • • •
            Underground mining has been the major method for production of several metals but is increasingly
            less common in die United'States.  Underground mining activities typically have significantly less
          	SSffiSS	£* suxgce	ffSHSSS	liHS,	fe-SSJaS	ttS&Bta.	.IMS,	is	due both to the fact that less
            waste rock is mined with ores that are mined'underground, and the fact that waste material can be
            "^ to, backfill mined out spaces. However, large underground openings such as slopes can cause
           s^^?^,0£ ^Y?? a*_*®.?1?*!?^»^suiting m significant disturbance to structures, roads, drainages,
           etc.  Drainage from underground mines also may cause significant alteration to the quality of surface
           water and can affect groundwater quantity and quality.
           SeVeraI underground mining procedures rely on the natural support of the ground, including:

                •   Room and Pillar. This method is suitable for level deposils lhat are fairly uniform in
                    thickness, ft consists of excavating drifts (horizontal passages) in a rectilinear pattern so
                    that evenly spaced pillars are left to support theoverlying material.  A fairly large portion
                    of the ore (40%-50%) must be left in place.  Sometimes the remaining ore is recovered by
                    removing or shaving the pillars as the mine is vacated, allowing the overhead to collapse or
	making future collapse more likely.

	i	2	Open.Stope. In competent rock, ft is possible to remove all of a moderate sized ore body
	''	I' resulting in an opening of considerable size.  Such, large, irregularly-shaped openings are '
                   called slopes. The'.mining of large inclined ore bodies often requires leaving horizontal
	P  ^acr^*®=°J^,^                	?° prevent collapse of the walls.

          Some other degree of support is required hi most underground nunes.  The basic concepts of the
          methods described above, gmjgeaended to permit working hi less competent rock to allow
	"	extraction of a greater percentage	of the	ore, by using variotis methods	of permanent or temporary
          support in order to prevent or delay collapse.
in n ill i in iiiini in i in n in in nil     i|niinniini ii i mi n i linn 111 iiiiiiiiini  iiiiiiiiiiifiiiiiiiiiiiiiiniiiiiiiii^^	a	•	^	•*•:,„	,	,,	   <   	






                                                       3-6                              September 1994

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EIA Guidelines .for Mining	'      Overview of Mining and Beneficiation


Underground mining methods that use these temporary or permanent methods of support include the
following:


     •   Longwall. In level, tabular ore bodies it is possible to recover virtually all of the ore by
         using this method (in the United States, only coal is known to have been mined using
         longwall methods).  Initially,.parallel drifts are driven to the farthest boundary of the mine
         area.  The ore between each pair of drifts is then mined along a continuous face (the
         longwall) connecting the two drifts.  Mining proceeds back toward the shaft or entry, and
         only enough space for mining activities is held open by moveable steel supports. As the
         longwall moves, the supports are moved with it and the mined out area is allowed to
         collapse. Various methods can be used to break up and remove the ore. In many cases,
         the rock stresses that are caused by the caving of the unsupported area aids in breaking the
         material, in the longwall face.

     •   Shrinkage Stoping. In this method, mining is carried out from the bottom of an inclined
         or vertical ore body upwards, as in open sloping.  However, most of the broken ore is
         allowed to remain in the stope in order both to support the stope walls and to provide a
         working platform for the overhead mining operations.  Ore is withdrawn from chutes in the
         bottom of the stope in.order to maintain the correct amount of open space for working.
         When mining is completed in a particular stope, the remaining ore is  withdrawn, and the
         walls are allowed to collapse.                  ..-•'.

     •   Cgt and Fill Stoping.  If it is undesirable to leave broken ore in the stope during mining
         operations (as in shrinkage sloping), the lower portion of the stope can be filled with waste
         rock and/or mill tailings. In this case, ore is removed as soon as it has been broken from
         overhead, and the stope filled with waste to within a few feet of the mining surface.  This
         method eliminates  or reduces the waste disposal problem' associated with mining as well as
         preventing.collapse of the ground at the surface.

     •    Square-set Stoping. Ore bodies of irregular shape and/or that occur in weak rock can be
         mined by providing almost continuous support as operations progress. A squareset is a
         rectangular, three-dimensional frame usually of timber, which is generally filled with waste
         rock after emplacement. In this method, a small square section of the ore body is removed,
         and the space created is immediately filled by a square-set.  The framework provides both
         lateral and vertical support, especially after being filled with waste. Use of this method
         may result in a major local consumption of timber and/or other materials utilized for
         construction of the sets.                           -

     •    Top Slicing. Unlike the previously described methods in which mining begins at the
         bottom of an ore body and proceeds upward,  this procedure involves mining the ore hi a
         series of slices from the top downward, first removing the topmost layer of the ore and
         supporting the overhead with timber.  Once the top layer of an area is completely removed,
         the supports are removed and the overlying material allowed to settle onto the new top of
         the ore body.  The process is then repeated, so that as slices of ore are removed from the
         ore body, the overburden repeatedly settles.  Subsequent operations produce an ever-
         thickening mat of timber and broken supports. This method consumes major quantities of
         timber.
                                                                                        1994

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     i ill	i
'I'Oyeryiew of Mining and Benefidation	EIA Guidelines for Mining
    i                     '"                     i                            ''

 Additional methods of underground mining' involve procedures in which ore is broken by removing its

                                K*d	as	the	ore	mass	subsides	to break	the	ore	into	manageable
	- pieces.  JMds based on Ais priiuqpa include:

               ;   ,    •                •          .        •    ,	    i,
                  *   Block Cavjng. Large massive ore bodies may be broken up and removed by this method
                     with a mmfntfim of direct handling of the ore required.  Generally, these deposits are of
          =           sucn f sizethat they would be mined by open-pit methods if the overburden were not so
                     thick. Application of this method begins with the driving of horizontal crosscuts below the
                     bottom of the ore body, or below that portion which is to be mined at this stage.  From
                     these passages,' inclined raises are driven upward to the level of the bottom of the mass
                     which |s to be broken. Then a layer is mined so as to undercut the ore mass and allow it to
                     setfle ,?nd'breakup. Broken ore descends through me raises and can be dropped into mine
                     cars for transport to the surface.  When waste material appears at the outlet of a raise it
                     signifies exhaustion of the ore in that interval. If the ore extends to a greater depth, the
                     entire process can be continued by mining out the mass which contained the previous
      i               working passage.
llllllllllllllllll I 111	Ill III 11  IN III          —70 J-——O		
                                                                                     I''
                 *   Sublevel Caving.  In this method, relatively small blocks of ore within a vertical or steeply
                     sloping; vein are undercut within a slope and allowed to settle and break up.  The broken
   1                  ore *l|!fl Hi?*11 into rais68 and dropped into mine cars. This method can be considered
                     as an intermediate between block carving and top slicing.
           NaturaUy mere are many variations and combinations of the basic methods discussed above. For
           exanjiple, a stope which is not quite capable of standing open without support may be. maintained by a
           i&$ of single timbers (or stalls) placed from wall to wall in a system called stall sloping. Many of
	the variations	and	combinations	of underground mining utilized today have been developed hi
           response to specific or unusual characteristics of the ore being mined  Mining methods used in the
          production of specific ores are presented by ore subcategory in subsequent sections of this chapter.


„„;	'	i	MM	.IS	,SS	.Solution Mining
             m ::::,::„„:	::,;	=::—:•  '          ,  ,                  '   ,       ,             • f  '       ,  '
          This is a method of underground mining that is applicable to certain ores under certain geohydrologic
          conditions. In principal, a series of wells are drilled into the ore body and a solvent is circulated
          through the ore-bearing formation by injection through some of the wells and withdrawal through
          owners. Use of me method has obvious geochemical restrictions based upon the amenability of the ore
          minerals to solution and the cost and practicality of solvents, and based on concerns related to
          groundwater quality. Hydrologic requisites include: (1) the host rock must be permeable to
     |      J  J  .   __  .        	•'	'	•	'	'	•"'	'	»	•	             	•	*
	£S£J2	225	£2	ii	=	Ill	!??!	HfiJ*	OYerllln	and	underlain by impermeable formations or
	ro^c "nte ttejeajtoldiie	vertical	low	oj fluids,	Jn	situ	solution mining is at present applied most
          widely to uranium and copper deposits in suitable geohydrologic settings.
          Although there is little disturbance of the bulk properties of the surface and underground materials at
          an in fitu solution mine, the effects of the operation on the quality of underground water can be
          enormous.  In order to solubilize the ore minerals, the chemistry of the groundwater must be
                                                     -3-8                              September 1994

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 EIA Guidelines for Mining	   •  •- '	•	Overview of Mining and Benefidation

 drastically altered by 'the introduced solvents. In addition to the ore minerals, other materials are
 dissolved by the solvent action and these, too, enter the groundwater, generally rendering it
 unacceptable for human or animal consumption and often presenting a hazard of further contamination
 if the altered groundwater moves out of the mine area and into surrounding areas.  Provisions for
 emergency cleanup and post-mining restoration of the groundwater often are required prior to
 issuance of permits for this type of operation.

 3.1.4   MINING WASTES AND WASTE MANAGEMENT

 The wastes generated by mining operations (as opposed to mills) in the largest quantities, and that
 present the most significant environmental impacts during and after mining, are mine water and waste
 rock.  These are described in the following two subsections. .Other wastes are generated in much
 smaller quantities, and they generally have much less environmental significance.  Many of these
 wastes are described in the commodity-specific discussions in Section 3.3. (It should be noted that
 the use of the terms "mining waste" and "waste management unit" in this document does not imply
 that the materials in questions are "solid wastes" within the meaning of the Resource Conservation
 and Recovery Act.)

3,1.4.1    Mine Water

Mine water is water that must be removed from the mine to  gain or facilitate access to the ore body.
For surface mines, mine water can originate from precipitation, flows into the pit or underground
workings, and from groundwater aquifers that are intercepted by the mine.  Mine water can be a
significant problem at many, mines, and enormous quantities  may have to be pumped continuously
from the mine during operations. Dewatering can result hi significant groundwater drawdowns, and
this in turn can result in the loss of streamflows as well as wetland and riparian habitat hi some areas.
Uses of mine water can include:

      •   Dust control  on the mine site (with or without prior treatment, depending on its quality and
          regulatory requirements).                                                "

      •   Process water hi the mill circuit (again, with or without prior treatment).

      •   Discharge to surface water pursuant to an NPDES  permit, which would include effluent
          limits on the discharge (limits would be either the 40 CFR Part 440 effluent units on mine
          drainage or more stringent limits if those were necessary to protect water quality).

When a mine closes, removal of mine water from the mine generally ends.  Underground mines can
then fill (or partially  fill) and mine water may be released through adits, or through fractures and
fissures that reach the surface. Surface mines that extend below the water table fill to that level when
pumping ceases, either forming a "lake" hi the pit or inundating and saturating fill material.
Recovery of groundwater to or near pre-rnining levels following the cessation of pumping can take

                                             3.9                               September 1994

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                                  and Beneficiation     _     EIA Guidelines for Mining
ilH         Mlllf'ii            '          	IIMM^           	ill	'iiiiA   	El!	IMtaaMM'MHriHJHHMVmiHp*M4>lmn^MK'^HI	     '
	'	'"""•'	'"'^^      	522SJ5	™,5SS	£222il?	fiSSS?,	£2	SSLlES groundwater drawdown (e.g.,
             reduction or elimination of surface water recharge) may continue to be felt for decades or centuries
             1 in i''' T liiiiiiiiiiinniinn, nil! 11,1, iiiiiiiiiiiiiiiiiiriiiiiiiiiiiininii: 
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  EIA Guidelines for Mining	      Overview of Mining and Beneflciation

  disposing of waste rock down slope from the crest of a ridge and represent the most common form of
  waste rock dumps (BCMDC, 1991). Heaped fills or waste piles are constructed in areas of flat
  terrain where available topography and other factors require.

  Regardless of the layout of the unit, waste rock dumps are generally constructed on unlined terrain,
  with underlying soils stripped, graded, or compacted as regulations and engineering consideration
  require. Such conditions may include steep foundations of unconsolidated material or partially
  saturated terrain that may not support the weight of fill material. Rock is hauled to the face of the
  unit in trucks or by conveyor systems and dumped.  Surface grading of fill material is typically
  performed to provide haulage trucks access to the working face.  Most commonly, waste rock is
  deposited at the  angle of repose. If multiple lifts are constructed, or if stability of the dump is a
  concern, side slopes may.be graded. Additionally,  final dump slopes may be graded during
  reclamation activities.

 Depending on site hydrology and regulatory constraints, drainage systems may be incorporated into
 dump foundations.  In areas of ground water intrusion or where catchment areas channel substantial
 surface water flows into the dump, drainage systems help to prevent instability due to foundation
 failures from saturation (BCMDC,  1991). Drainage systems may be constructed of gravel-filled
 trenches or'gravel blankets, with capacity and configuration determined according to site-specific
 conditions. Dump toe drains may be particularly favored to reduce pore pressure near the face .of the
 structure to prevent toe spreading or local slumping.

 Equally important are surface water and run-on controls.  Such controls are often necessary to
 maintain stability .and prevent mobilization of fines as well as erosion of exposed slopes.  Upstream
 surface water diversion ditches and rock drains are options often incorporated into design for these
 purposes.

 3.1.5    RESTORATION AND RECLAMATION

 Restoration activities often are conducted during surface mining activities in order to reduce
 environmental impacts and enhance visual aesthetics in the mining area. Although these restoration
 activities do prove valuable, they do not replace or lessen the necessity for full and comprehensive
 land reclamation at the completion of various staged mining activities.  Temporary restoration
 activities may involve tasks such as  landscaping in non-mining areas, soil stabilization by replacement
 of native grasses on spoil bank slopes, and using temporary vegetation covers on topsoil and other
 stockpiles.

 Restoration activities conducted during underground mining operations are similar to those used in
 conjunction with surface mines, but are more limited since the waste piles developed as a result of
underground mining are relatively smaller.  Restoration activities  conducted during underground
                                             3-11                              September 1994

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                                                                                                      SriKsSSfi' l&F i*
                                                                                    .......          ....... —
                                                     .                   .....
                                                ..... im^      ......        .
             periodc seaing of drift ennywaysto prevent mine drainage.
                                            ^ ...... ~ ....... ?!°sion contro1 measures around the mining site, and the
                                              .....
" '""' '  ............................. ^li!!!16 land reclamation activities begin upon ...... congletion of ..mining or of planned unit mining
" ..... Bli [[[ st^S" ..... These s^ges can be three to five yearplans ...... for ...... large ..... mines! ...... or: ..... one- to three-month events .
[[[ ftF ...... SL22S ...... 2S2| operations.  Land reclamation activities are not temporary restoration measures
........... "' ................. ........... ' .................. .......... .........  tafce* to «
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  EIA Guidelines for Mining       ...                 .     .  Overview of Mining and Beneficiation


       •   Removing waste rock and using it as backfill in underground workings or the open pit.
           This can be prohibitively expensive, and is generally not an economic option after the waste
           rock has already been placed in dumps.  In addition, nonreactive (i.e., not acid forming)
           waste rock can be used as construction material during successive stages of mine
           development (e.g., roads, tailings dams, water diversion berms, building foundations,
           underdrains) and for off-site construction.

      •  ' Regrading steep slopes of the dump to slopes less than the angle of repose, thus enhancing
           long-term stability. Regrading can include incorporating flat benches at intervals of the
           slope to  reduce runoff velocity and provide another surface suitable for revegetation.
           Depending on the size of the waste rock, it may be appropriate to cover slopes with topsoil
           and revegetate.

      •   If the dump contains acid-generating waste rock, reducing infiltration becomes even more
           important.  This can be accomplished by lining the top surfaces of dumps with synthetic
           materials or clay.  Then, the cap or liner is covered with a protective layer of fine-grained
          material, covered with topsoil, and revegetated; alternatively, the surface can be covered
          with large rocks and boulders.  When revegetating, particular care must be taken in
          selecting the plant species, since they must resist extreme cycles of drought and saturation.
          In addition, species must be shallow-rooted to avoid penetrating clay  caps.

3.2    ORE DRESSING (BENEFICIATION)

Most ores contain the valuable metals disseminated in a matrix of less valuable  rock called gangue.
The purpose of ore beneficiatibn is the separation of valuable minerals .from the gangue to yield a
product which is much higher in content of the valued material.  To accomplish this, ore generally
must be crushed and/or ground small enough so that each particle is composed predominantly of the
mineral to be recovered or of gangue. This separation of the particles on the basis of some difference
in physical or chemical properties between the ore mineral and the gangue yields a concentrate high in
values,  as well as waste (tailings) containing  very little value.  Overall recovery is optimized
according to the value (and marketability) of the concentrate produced.


Many properties are used as the basis for separating valuable minerals from gangue, including:
specific gravity, conductivity, magnetic permeability, affinity for certain chemicals, solubility, and the
tendency to form chemical complexes.  Processes for effecting separation may be generally considered
as: gravity concentration, magnetic separation, electrostatic separation, flotation, and  leaching.
Amalgamation and cyanidation are variants of leaching which bear special mention.  Solvent
extraction and ion exchange are widely applied techniques for concentrating metals  from leaching
solutions, and for separating them from dissolved contaminants.

3.2.1    GRAVITY  CONCENTRATION

Gravity-concentration processes exploit differences in density to separate ore minerals from gangue.
Several  techniques (e.g., jigging, tabling, spirals, sink/float separation) are used to  achieve the
                                             3-13                              September 1.994

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            Overview of Mining and Beneficiation                                EIA Guidelines for Mining

            •HI  i i iiinniiniliin inn i mi 11 mi inn IHHHMHH innninn innnnnnninnnninn i in iiiinnnnninn  l"i niiiini iiinnnniinniinnninninnniiinin m i iiiinin in i nn in in  inn i nun IHMHHMIH HIM HIM in  n  11 IIIIHIH mil i i n nn linn i i niniini nun iiinii  in i mil i HIM |       inn n imp iiiinin MM nlin nun i iniiinn
            separation.  Each is effective over a somewhat limited range of particle sizes, the upper bound of
                   ; set by the size of the apparatus and .the need to transport ore within it, and the lower bound
            by the point at which viscosity forces predominate over gravity and render the separation ineffective.
            Selection of a particular gravity-based process for a given ore will be strongly influenced by the size
            to which the ore must be crushed or ground to separate values from gangue,. as well as by the density
            difference and other factors.
            Ill III  llllllllllll	lIMIillllllllllllll       	Ill III
      1(1(11	illl'll
lull ill
                    i ii   i     n             i,                                      p
   Gravity concentration typically involves three general steps, the first to remove grossly oversized
   material from the smaller fraction that contains the valuable mineral (generally gold), the second to
   concentrate the mineral, and the third to separate the fine values from other fine, heavy minerals.
   The same typtof^yapn^. is pften.used in more than one step; for example, an array of jigs may be
   employed to handle successively finer material (Flatt, 1990).

   Classification (sizing) is the initial step in the beneficiafion operation.  Large, oversized material
   (usually over 3/4 inch) is removed.  A rough (large diameter). screen is usually used. This step may
   be feji by a bulldozer, front-end loader, backhoe, dragline or conveyor belt.  Within the gold placer
   industry, this step is also referred to as roughing (EPA, 1988a). Previous studies have indicated that
.  the practice improves the efficiency  of gold recovery and reduces water consumption (Bainbridge,
   1979).    1-                   •                  '              '    '    "             '     '     _ ..... ; ........ ; ..... _
                                                           •                               •
          After ..... SX,iSSi,i:2222!- ...... SmS^JSFB61 n13161*3! during sizing, ore is subject to a coarse concentration
          stage; This step, also referred to as cleaning, may employ trommels or screens.  Other equipment
          used in the coarse concentration stage includes sluices, jigs, shaking tables,  spiral concentrators and
          cones.  Depending on the size of the particles, cleaning may be the final step hi beneficiation (Flatt,
          1990; Silva, 1986).              [[[ : ....... ..... ............. ' [[[
                                           1 1                                             ii
          Fine concentration is the final operation used to remove very small values from the concentrate
          generated in the, previous stages. Many of the previously identified pieces of equipjnent can be
          gjljgjj^l g_. ^^ ^qjjJSfon. sensitivity.  Final separation uses jigs, shaking tables, centrifugal
          concentrators, spiral concentrators or pinched sluices.

          The following is a summary of the equipment commonly used in beneficiation. One of the key
          detenrunants in selecting equipment is the volume of material that will pass  through each step within a
          given time period.  Rates for ore handling for the equipment discussed below are included where the
          information was available.
          3.2.1.1    Sizing
                                                                              '       '    i
          Sizing is the physical separation of material based strictly on size. The sizing step removes large
          rocks prior to additional beneficiation. The waste generated is usually solid and is much lower in
111 lilllllllll I Hill	IIIIII 1111  i 11 Ilillilllll	1 Hill 111 III 11111  Illllli  lllllli i   • 1	1	

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 EIA Guidelines for Mining                                Overview of Mining and Benefication

 volume compared to the ore that passes through. .Discharge material may be used for other
 applications including-road aggregates. This step typically involves the ore being loaded into a
 grizzly, trommel or screen, or a combination thereof.

 A typical grizzly consists of a large screen or row of bars or rails set a specific distance apart (2 to 6
 inches) such that undersized (gold-bearing) material can readily pass  through while oversized material
 is rejected. Typically, the grizzly would be inclined to ease the removal of the rejected material.
 Water is usually used to move material through the grizzly and wash off any fines that  may be
 attached to larger fragments before they are discarded. The undersized material drops onto a
 trommel, screen, or sluice depending on the operation.  Grizzlies may be stationary or  vibrating
 (EPA, 1988a).

 Trommels are wet-washed,  inclined, revolving screens. They usually consist of three chambers, the
 first uses a tumbling action and water to break up aggregated material.  Successive chambers are
 formed of screens or punched metal plates (smaller holes first) that allow the selected sized material
 to pass through.  The screens  are typically 3/8 inch in the second chamber and 3/4.inchIn the final
 chamber.   Material passing through the screens is directed for further concentration.  Material passing
 through the trommel may be returned for a second pass or discarded  (Cope and Rice, 1992; EPA,
 1988a).

 A fixed punchplate screen (also called a Ross Box) consists of an inclined plate with holes ranging
 from 1/2 to 3/4- inches. Ore is placed onto the plate where nozzles wash the material with a high-
 pressure water stream. The undersized (desirable) material is washed to the outside of the plate
 where it is fed into a sluice designed to handle 3/4 inch material.  The oversized material is directed
 down the plate which typically has riffles to collect coarser gold. Oversized material passing off the
 plate is discarded.

 Screens function to separate oversized, undesirable material from the  ore.  Screen size (usually 1/2 to
 3/4 inch) is selected based on ore characteristics.  Screens may be fixed or vibrating.  The action of
 bom is similar although vibrating screens speed the rate of particle separation.  The concentrate
continues  for further concentration while the oversized material  is removed via a chute or stacker
 conveyor belt. Different sized screens may be used to sort material into different sizes  for use as
 road construction aggregate or other purposes.

3.2.1.2    Coarse Concentration

 Separation in the coarse concentration step involves particle density rather than size. Sluices are the
pieces of equipment most commonly used by gold placer mines  in the coarse concentration step
 although jigs and screens may also be employed.  The wastes are discharged to a tailings pond, also
called a recycle pond or settling pond.  Most of the material that enters the sluice exits as waste. The


                                              3-15                               September 1994

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                                                                                                       i	liiUiJI	liiH^
              Overview of Mining and Benefication	•..	EIA Guidelines for Mining
             gold and other heavy minerals settle within the lining material while the lighter material is washed
             through.  Coarse concentration generates the largest volume of waste during beneficiation.
             A sluice consists of a long, narrow, inclined trough lined with riffles, perforated screens, astroturf,
    ;;;	1=^^  	":i' corduroy, burlap, or a combination thereof. The sluice mimics the .conditions that .caused the
             formation of the placer deposit initially.  Ore is placed at the high end of the trough and washed with
             aspreamofwater.  Gold and other dense minerals settle between me riffles or in the lining while the
             lighter material is carried through the sluice. Longer sluices are used for preliminary concentration.
             Shorter, wider sluices are used following preliminary separation to separate fine gold from black
             sands. The length, grade, riffles and lining are adjusted to suit the nature of the ore.  However,
             slopes of one to two inches per foot are typical.
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            Riffles are bars, slats, screens or material that act to create turbulence and variation of water flow
            within the sluice.  This action increases the efficiency of gravity separation. Riffles have ranged in
            s£zef from 12 inches wide, 12  inches high and 12 inches apart to 1 inch high, 1 inch wide and 2 inches
            apart.

     ™™lkHungarian riffles arc angle irons mounted perpendicular to the sluice box.  The vertical angle of the
            angle irons may be adjusted to affect the degree of turbulence generated and marinrnrt gold
     ^j^tieposidon.  Astroturf, carpet  or coconut husks are sometimes placed between and under the riffles to
    	mMMFwtfttti7x their efficiency. The units are usually constructed so that sections of the riffles may be
    iijJJ^fSPSESl	mi	£8,folt* can ** recovered from the turf. As mentioned above, the height, spacing and
    2S&2*	'construction of the riffles may be adjusted to maximize efficiency of separation depending on the
            character of the ore.
                          has also been tested and/or used as riffles and liners.  Expanded metal riffles are
            employed at some operations.  Like the hungarian riffles, the height, size-and spacing is determined
            by the orc and sections are removable for cleaning.  Miscellaneous materials including longitudinal or
    •!;•== ri?!^0*^..?1!^0"?^]?^!*8* blocks, rocks, railroad ties, cocoa mats, rubber and plastic strips have also
                    S°SSl	lilting used as riffles by different placer operations (EPA, 1988a).
=^^^^	!!!='3.2.O,     Une Concentration
                              '•	'	'	'	'	•'	"'	'	'"'	'		'	'	'	'	1|I'"LIJ1	'	"	»•'	"	'	""	J'" '"'	Nl	'	'	'"'''	"'	-	
               x the ore is concentrated, typically through a trommel and sluice, most waste material has been
     	,	,	,	,	_	* £J5£	SSSSHSS:	ISS,	SSSSSSSS&Rpy men be subjected to fine concentration
               ,,.......                            	"	'	••	•	n	
                    including jigs, shaking tables and pinched sluices.  Depending on the nature of the
                            ie equipment, 80 to 95 percent of gold can be recovered from the concentrate at this
                      SSl ..... S .....  l49§? ...... I* ...... §.?"ny (often called slimes), and is low in volume compared to that
                      5 .....  * ottw ..... stages.
•••••^   	11!" Sill! I'iJiiiil'W: lillliiillK    flillfllll, lililllH^ .i. IIIIIIIIIIIII", I ill	I	111'! flililC'll Sill1: liilNlllH^^^^ II
|H     	!^y-:?!!^	:!?-!?;"	"	"!	'•	i!"	ll>"	•	'	'	'"	
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3-16                               September 1994
                                            '"
                                                        ...... fl»

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 T3A GviideBnes for Mining   .                            Overview of Mining and Benefidation

 Jigs are settling devices that consist of a screen through which water is pulsed up and down via a
 diaphragm or plunger numerous times per second.. A layer of rock or steel shot referred to as
 ragging may be placed on the screen to  accentuate the up and down motion.  Slurry is fed above the
 screen.  The agitation keeps die lighter material in suspension which is then drawn off: The heavier
 material falls onto or through the screen and is collected as concentrate.  Efficiency is increased by
 varying the inflow rate, pulse cycles and intensity. Jigs may handle from 7 to 25 tons per hour, and
 can handle particles ranging from 75 mm to 25 mm.  At some operations, jigs are also employed hi
 the cleaning stage. (Macdonald, 1983; Silva, 1986).

 Shaking tables consist of small  riffles over which a slurry containing fine ore is passed. The gold
 settles into the riffles and, through a vibrating action, is directed to one side of the table where it is
 collected.  The tails are passed  across the middle of the table or remain in suspension.  Middlings, •
 material that is partially settled, may be collected. Heads and .middlings are commonly reprocessed
 on multi-stage tables. Shaking  tables can handle materials from 15 am to 3.0 mm (EPA, 1988a;
 Macdonald, 1983).

 Spiral concentrator is a generic term referring to a method of separation rather a specific piece of
 equipment.  Ore concentrated from previous steps is fed with water into the top of the spiral and spins
 down through the spiral. The heaviest materials are concentrated toward the center of the spiral while
 lighter material moves to the outside.  Concentrates are collected from the center of the spiral while
the tails pass down the entire spiral.  Large operations may employ multiple spiral concentrators in
series to handle a wide range of sizes. Humphreys concentrators, as one example, can be used to
separate particles between 100 urn and 2 mm in diameter.  These machines can handle low feed rates
 (1.5-2 tons per hour) and low feed density (EPA, 1988a).

Centrifugal concentrators or bowls were typically used in dredges but may also be used in other
operations.  Slurry is fed into the top of the circular machine. Driven from the bottom, the ulterior
portion spins on its vertical axis, driving the slurry against a series of concentric circular riffles or
baffles.  The lighter material (tails) is driven up the side of the bowl while the heavy material
 (concentrate) collects on the bottom or in the riffles (Cope and Rice, 1992).

Pinched sluices work on the concept that as a fine feed is exposed to an opening, the arc formed by
the heaviest particles dropping will be much narrower than the arc formed by the lighter materials.  A
divider placed perpendicular to  and below the pinched outfall lets heavy materials (concentrate) collect
 on one side while lighter material (tails) can be collected and reprocessed separately or directed out of
 the operation completely.  Reichert cones, which are based on the pinched sluice principle, can handle
 75 tons per hour and recover particles in the minus 10 to plus 400 mesh range (45 um to 0.5 mm)
 (Gomes and Martinez, 1983).
                                             3_17                               September 1994

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                                                                          ESA
       Magnetic separation i^see Section 3.22) is not commonly used in gold placer mining but may be
    ...... • .............. : W1^ «*« ..... magnetite ...... is ..... a ..... component of the black sani .............. Ibis ...... technique is usedto remove
       de<^StatIcaUy ^^^ taas fro* the neutral gold. To be effective, the method should involve
       mutaple magnetic treatments followed by demagnetization steps so that the magnetite is removed
       slowly, not in a 'magnetically coagulated* form, that may bind gold particles within it.  Magnetic
       separation, when used, is one of the final steps of beneficjation.
      "  • i             "       ......................................... - [[[ ' ..................... "l   "12 ..... * ...... 1 ..... IIIIII ...... "; ....... II ........... 2IIiriZI~-I.~ ...... I' ..... II ..... - ....... I ..... • ...... I ...... ' ...... ''I ...... '
       3.2.1.4    Sink/Float Separation  "
                       *                  ,                        '                i
..... ::::i^                                                        ......                           ^
...... ™foices *£ ..... H?^ tp s*?3^ the ...... various ..... minerals ...... pn ..... the basis of density. The separation is achieved by
      ^^ the ore to a tank containing a. medium whose density is higher than that of the gangue and
      less than that of the valuable ore minerals. As a result, the gangue floats and overflows the
      separation chamber, and the denser values sink and are drawn off at the bottom, often by means of a
          ^ devator or similar COIttrivan<:?:  T^e s^ of material separated by this  method varies, and is
              l: OT *« densi|y a*1 viscosity of the medium. Because the separation takes place in' a
              *» fc*     d turbulence is minimized, effective separation may be achieved with a more
              S2 !E! !fefc5°J* Siavity-separation techniques. .Viscosity does, however, place a
             lS 2SP»«fcte size for practicable separation, since smaU particles settle very slowly
     limiting the rate at which ore may be fed.  Further, very.fine particles must be excluded, since' they
     mix with the separation medium, altering its density and viscosity.  Media commonly used for
     stak/float sej^on in the ore milling industry are suspensions of very fine ferrosilicon or galena
     ^ rSS: SSSSSSS particles may be used to achieve medium specific gravities as high as
     3-5, and are used m ^feyy-medium separation."  Galena aUows the achievement of somewhat higher
     pensjties of ore concentrate.        •                     '                        ".    '
    3.2.2    MAGNETIC SEPARATION
    Magnenc separation is widely applied in the ore milling industry, both for extraction of values from
    ore and for separation of different valuable minerals recovered from complex ores.  Magnetic
    separation is used in beneficiating ores of iron, columbium and tantalum, and tungsten. Separation is
    based on differences in magnetic permeability (which, although small, is measurable for almost all
    matenals)    * effective           r^ti   not normally considered magnetic. The basic process
        t                                                                     .
    mvolves *ansport of ore through a region of high magnetic-field gradient.  The most magnetically
    permeable particles are attracted to * moving surface, behind which is the pole of a large
                     ««     «  >    out ..... of the main stream of ore.  As the surface leaves the
                                       .....
    high-field region, particles are released into a hopper or onto a conveyor leading to further
    processing.

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 ELA. Guidelines for Mining	'•'           Overview of Mining and Beneficiation

 For large-scale applications, particularly in the iron-ore industry, large rotating drums surrounding the
 magnet are used. Although dry separators are used for rough separations, these drum separators are
 most often run wet on the slurry produced in grinding mills.  Wet and crossed-belt separators are
 frequently employed where smaller amounts of material are handled.                              '
                                   j
 3.2.3    ELECTROSTATIC SEPARATION

 Electrostatic separation is used to separate minerals on the basis of then* conductivity.  It is an
 inherently dry process using very high voltages.  In a typical application, ore is charged at 20,000 to
 40,000 volts, and the charged particles .are dropped onto a conductive rotating drum.  The conductive
 particles lose their attractive charge very rapidly and are thrown off and collected, while the
 non-conductive particles keep their charge and adhere by electrostatic attraction. They may then be
 removed from the drum separately.

 3.2.4   FLOTATION

 Basically, flotation is a process where  the addition of chemicals to an ore slurry causes particles of
 one mineral or group of minerals to adhere preferentially to air bubbles. When air is forced through
 a slurry of mixed minerals, the rising bubbles carry with them-the particles of the mineral(s) to be
 separated from the matrix. If a foaming agent is added  which prevents the bubbles from bursting
 when they reach the surface, a layer o? mineral-laden foam is built up at the surface of the flotation
 cell which may be removed to recover the mineral. Requirements for success of the operation are
 that particle size be small (typically flour-sized or less),  that reagents compatible with the mineral to
 be recovered be used, and that water conditions in the cell, not interfere with the attachment of
 reagents to minerals or to air bubbles;.

 Flotation concentration has become a mainstay of the ore milling industry because it is adaptable to
 very fine particle sizes of less than 0.01 mm (.0004 in.). It also allows for high rates of recovery
 from slimes, which are inevitably generated in crushing  and grinding and which are hot generally
 amenable to physical processing.  As a physico-chemical surface phenomenon, it can often be made
highly specific, allowing production of high-
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ii	
    i • nil in i in mi i in
in iiiiiiiiiiiiii in i
     Oyq^iew of Inning and Beneficiation _ _ EIA Guidelines for Mining
                                                                         j
     the bubbles to create a foam which may be effectively recovered from the water surface. Activators
     enhance the attachment of the collectors to specific kinds of particles, while depressants prevent such
     ffi±BBi ...........          ...... ,ffi fe^^y *** to a*1™ &<>&*<>* of particular minerals that have been    -
     depressed * «n earner stage of the milling process. In almost all cases, use of each reagent in the
    S2 ...... S ...... ,?ffi ...... JS« generally less than 0.5 kg (approximately 1 Ib) per ton of ore processed; at large-
    capacity mills, the total reagent usage can be high, since tens of thousand of tons of ore per day may
    be beneficiated. , The bulk of the reagent adheres to tailings or concentrates.

    Sulfide minerals .are all readily recovered by flotation using similar reagents in small doses, although
    reagent requirements and ease of flotation do vary throughout the class. Sulfide flotation is most
    often carried out at alkaline pH. Collectors are most often alkaline xanthates having two to five
    "ckbon atoms— for example, sodium ethyl xanthate (NaSjCOCzH). Frothers are generally organics
   , with a soluble hydroxyl group and a "non-wettable" hydrocarbon. Sodium cyanide is widely used as
    a pyrite depressant.  Activators useful in sulfide-ore flotation may include cuprous sulfide and sodium
    sulfide.  Other pyrite depressants which are less damaging to the environment may  be used to replace
   the sodium cyanide.  Sulfide minerals  of copper, lead, zinc, molybdenum, silver, nickel, and cobalt
   are commonly recovered by flotation.
                  »                                   i                  .      |  (      ,   .
^
   Minerals in addition to sulfides may be recovered by flotation (e.g., oxidized ores of iron, copper,
   manganese, the rare earths, tungsten, titanium, and columbium and tantalum).  Generally, these
   flotation processes are more sensitive to feed-water conditions than sulfide floats; consequently,
   oxidized ores can less frequently run with recycled water.  Flotation of these ores involves very
   different reagents  from sulfide flotation-and may require substantially larger dosages. Reagents used
   include fatty acids (such as oleic acid or soap skimmings), fuel oil, and various amines as collectors;
   and compounds such as copper sulfate, acid dichromate, and sulfur dioxide as conditioners.'

  3.2.5    LEACHING
                                                           «
  Leaching is the process of extracting a soluble metallic compound from an ore by selectively
  diving * m a wfeMe solvent such as  water, sulfuric hydrochloric acid, or sodium cyanide
  solution-  "H* ^ired metal is men removed from the "pregnant" leach solution by chemical
  P«cipftati°n or omer chemical or electrochemical process.  When ores are (or can be) so fractured or
  scattered m tenure that air and water can be made to percolate through them as they exist in the
  ground, then the ores can be profitably leached in-situ (in place) without being mined. Ores  that are
  mined, but arc too low in grade to justify the cost of milling, can be recovered by placing the ore
  rock in large piles  on an impermeable surface and treating them with the leach solution, which is
  collected through a drain system at the bottom of the pile. This method is termed "heap" or "dump"
  leaching.  Heap leaching is widely used in the gold industry, dump leaching in the copper industry.
  Vat or tank leaching is similar to heap leaching, with the exception that the ore rock  is placed in a
                                                       3-20                             September 1994

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  EIA Guidelines for Mining	        Overview of Mining and Beneficiation

  container (vat) equipped for agitation, heating, aeration, pressurization, and/or other means of
  facilitating the leaching of the target mineral.

  Ores can be leached by dissolving away either the gangue or the value in aqueous acids or base,
  liquid metals, or other special solutions. Typical leaching situations include:

       •   Water-soluble compounds of sodium, potassium, and boron which are found in arid climates
           or under impervious strata can be mined, concentrated, and separated by leaching with
           water and reciystallizing the resulting hrihes.

       •   Vanadium and some other metals form anionic species (e.g., vanadates) which occur as
           insoluble ores.  Roasting of such insoluble ores with sodium compounds converts the values
           to soluble sodium salts (e.g., sodium vanadate).  After cooling, the water-soluble sodium
           salts are removed from the gangue by leaching in water.

       •   Uranium ores are only mildly soluble in water, but they dissolve quickly hi acid or alkaline
           solutions.
                  >
       •   Native gold which is found in a finely divided state is soluble in mercury and can be
           extracted by amalgamation (i.e., leaching with a liquid metal).

      •  Nickel can be concentrated by reduction of the nickel with ferrosilicon at a high
        .  temperature and extraction of the nickel metal into  molten iron. This process, called
          slop-ladling, is related to liquid metal leaching.

      •   Certain solutions (e.g., sodium cyanide) dissolve specific metals (e.g., gold) or their
          compounds, and leaching with such solutions immediately concentrates the values.
                     \
Leaching solutions can be categorized as strong, general solvents (e.g., acids) and weaker, specific
solvents (e.g., cyanide). The acids dissolve certain metals present, which often include gangue
constituents (e.g., calcium from limestone). They are convenient to use, since the ore does not have
to be ground very fine, if at all (i.e., approximately 5 to 30 cm (2  to 12 mches) in diameter), and
then separation of the tailings from the value-bearing (pregnant) leach solution is not difficult.  In the
case of sulruric acid, the leach is cheap  but gangue constituents hi addition to the value  are dissolved.

Specific solvents  attack only one  (or, at most, a few) ore constituents), including the one being
sought. Ore must often be crushed or finely ground to expose the values, although this is not always
necessary.

Countercurrent leaching, preneutralization of lime in the gangue, leaching in the grinding process,
and other combinations of processes that simplify or improve  the effectiveness of the leaching
                                             3-21                               September 1994

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,	i	„:	|	;	;	;	i	;
               i                                                                         ,
                                                                -j           ,  ,      ',    'J:    , ,
           • Overview of Mining and Beaeficiation                                ETA Guideline*: for Mining
                                                                  .  '                >    (         i
                                                                                        I
             prtjcedure are often seen in the industry.. The values contained in the pregnant leach solution are
	recovered	By one of several methods, such as:          .                   '
 iiiiiiiiiii 1111 n (  i III
 i iiiiiiii  i inn niliini
                      Precipitation. The process of separating mineral constituents (i.e., values) from a solution
                      by chemical means, by evaporation, or by changing the temperature and/or pH of the
                      solution.                                                 •	'

                      Electrowinning.  The recovery of metal values from solutions by an electrochemical
                      process similar to electrolytic refining.  Insoluble (long-life) anodes are used, with the
                      desired metal produced as or on a cathode.

                  •   Carbon Adsorption.  The target mineral is adsorbed onto activated carbon and further
                      concentrated.
                                        .  -    ,      .  ••    "•           • '   ,   ,'   •  •,  • il  	
                  •   Cementation. The process by which a metal is precipitated or "cemented" out of solution
	B	|	as	a finely divided	metallic	product	by	Replacement	with	less	active^metal.	For example,
"=:'~"""'"•"' :	=l":	""'	wfraT'copper	s5SoiT(Cj3o§	¥brougji	into	contact	^fli scrap	tonplates^	(Fe),'the
               	SJpjgSf"	j™^^	jg£	g^j	oiFrae	scrap	plates	^g	g£	j^—	~—	g-	s'ojjtipn	_...__i_	^^	
              :        copper is then removed by washing the scrap plates.

            Amalgamation represents a special application of leaching and/or the recovery of the leached mineral.
            Amalgamation	is	a Pjcpcess	by_	which	mercury,	in	its	natural	liquid state, is alloyed with some other
            metal to produce an "amalgam" (a solution containing mercury and another metal(s) in liquid form).
            This process is applicable to free milling precious metal ores, which are those in which the ore is
lllliiB    IH!'1 free, relatively coarse, and has clean surfaces.  The current practice of amalgamation in the United
	States	!2	ISBlSli	fp,	SHPH-scate barrel amalgamation of a relatively small  quantity of high-grade,
            gravity-concentrated gold ore.  The gravity concentrate" is ground hi an amalgam barrel with steel
            balls or tods before mercury is added. This mixture is then gently ground to bring the mercury and
            gold  into intimate contact. The resulting amalgam is collected in a gravity trap. Although the
            amalgamation process has, in the past, been used extensively for the extraction of gold and silver
            fi^jBverlzediores, m recent years it has largely been superseded  by cyanidation processes, as
	:	described in Section 3.3.1.
           .   ^IIISK^    	sss, •TS'aiKutsa	                  .   ^^WE	avt '	w	•iSE•;* mr;jcraHW"^i-w	•»••	flSWil	   •      	i	-v'-l	! "•''•"•' WBt.wpsaai	s	si'	''fin
                                                                                  	i«)«^^^^    	»;»Hiiin	•/•'"if/;!.!!	iii^/ijiMiiiiiiiM^^^^
                    _              	iin^^^^^^^
           £i&£	Siiiil3All0fi,1ffi4Slls	AND WASTE MANAGEMENT
           Tgilings are the wastes generated in by far the largest quantities by beneficiation operations that use
           flotation and gravity separation. This section describes the most common method of managing and
           disposing of tailings from metal mines.  Tailings from gravity separation are described in the
           discussion of gold placer mining hi Section 3.3.2.  Leaching operations also generate enormous
           quantities of spent ore and small quantities of process solutions:  the management of wastes from heap
           leaching is described in the discussion of gold mining (Section 3.3.1), the industry sector hi which
           heap leaching is most commonly practiced; the management of wastes from dump leaching is
               iiiiii  i i i  iini  in i iiiiiiM  iiiiiiiiiii i 1 11  111   ii in i iiiiiiiiiii    i nil  i il iiiiiiii iiiiiiii i n in  iini iini  i iiiiiiii iiiiiiiiiii 1  iiiiiiiiiii iiiiiiiiiii i   ii iiiiiiii in  i  MI in  i ill mi  i   i i i i  i in n ill 11 in i   HI"	il
                                                         3-22                              September 1994

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 E1A Guidelines, for Mining	   Overview of Mining and Beneficiation

. described in the discussion of copper mining (Section 3.3.4), the industry sector .in which dump
 leaching is most commonly practiced.

 Tailings are the coarsely and finely ground waste portions of mined material that have been separated
 from the valuable minerals during beneficiation (crushing, grinding and concentration).  By far the
 larger proportion of ore mined in most industry sectors ultimately becomes tailings that must be
 disposed of.  In the gold industry, for example, only a few hundredths of an ounce of gold may be
 produced for every ton. of dry tailings generated.  Similarly, the copper industry and others typically
 mine relatively low-grade ores that contain less than a few percent of metal values; the. residue
 becomes tailings. Thus, tailings disposal is a significant part of the overall mining and milling
 operation.  The physical and chemical nature of tailings varies according to the ore being milled and
 the milling operations used to beneficiate the ore. The method of tailings disposal is largely
 controlled by the percent water content of the tailings.  Generally, three types of tailings may be
 identified based on then: water content; wet, thickened and dry.

 Most ore milling processes require the use of water to classify (grinding stage) and concentrate the
 valuable minerals.  Although dewaterihg of tailings  is a common final step prior to the transport and
 disposal of the tailings, an equal or greater weight of water remains with the solids in a slurry
 mixture. These tailings are known as wet tailings.  More recently, some mills have begun to
 significantly dewater tailings to where only 40 percent of their total weight is water. These tailings
 are known as thickened tailings.

 A few beneficiation operations, such as magnetic separation, may require little or no water for
 preparing the ore.  Tailings beneficiated with these methods are normally known as dry tailings.
 Magnetic separation extracts magnetic minerals, such as iron, from the nonmagnetic particles, which
 remain as tailings.  Although tailings from beneficiation operations may be considered dry tailings,
 they may contain a small weight percentage of water. In addition to the specific beneficiation
 operations that produce dry tailings, belt filtering (which removes liquids from tailings by transporting
 the tailings on a cloth belt over a vacuum box) results hi tailings with only 20 to 30 percent total
 weight in water. These tailings are also considered to be dry tailings.

3.2.6.1    Mine Backfilling

 Slurry tailings are sometimes disposed in underground mines as backfill to provide ground or wall
 support.  This decreases the above-ground surface disturbance and can stabilize mined-out areas. For
 stability reasons, underground backfilling requires tailings that have a high permeability, low
 compressibility, and the ability to rapidly dewater (i.e., a large sand fraction).  As a result,  only the
 sand fraction of whole tailings is generally used as backfill.  Whole tailings may be cycloned to
 separate out the coarse sand fraction for backfilling,  leaving only the slimes to be disposed in an
                                              3-23                               September 1994

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                                                        1       . •   •                      !'
              Overview of Mining and Beneficiation	     EIA Guidelines for Mining
              —   --                       -   ,        ,   ,  .      •   .     —     -       j     ;     ——     T-
  i	iii in
      kopoundmem.  To increase structural competence, cement may be added to the sand fraction before
      backfilling (Environment Canada, 1987).
 i ill iiii in i i  iniii 1 1 in i in i n in i 1 1 iiiiiiiiiiiiiiiiiiii  iiiiiiiii  i ii mil nil Mini i IIP ill 111   i          ,           i           ill
      3.2.6*2    Subaqueous Disposal

      Subaqueous disposal hra permanent body of water such as a lake, the ocean, or an engineered
      structure (e.g., a pit or impoundment) is also a possible disposal method.  The potential advantage to
      underwater disposal is that it may prevent the oxidation of sulfide minerals in tailings, thus
      prohibiting acid generation. However, there is substantial uncertainty regarding other short- and
      long-term  effects on the water body into which the tailings may be disposed (Rawson  Academy 1992;
      U.S. Bureau of Mines 1992). Canada's Mine Environment Neutral Drainage (MEND) program is
      currently studying subaqueous disposal.

inr Ifoji ...... tsnch-scale ...... 16-year simulation of deep-lake disposal using Ottawa River water by CANMET .
^~. ; ^(Canadian ..... Centre ...... for ..... Mineral ....... and ..... Energy Technology), Ritcey and Silver (1987) found that the •
                           ...... °IL25 ...... —IS?. ..... SBLSES ...... 22* ..... ll°,w, ...... XM^LSSS!!: ........... £JPley» etal- (1978),   .
             found ...... that ..... te ..... taHSoigs ...... ^ ..... cover ...... ia'axeas'onihe ocean ..... or lake floor and ...... cause ..... turbidity problems if
             the ..... disposal practice is not designed correctly.  There" are' little, data on the long-term efficacy and
             environmental effects of subaqueous "disposal ...... (Environment Canada,  1987), although this issue is  '
lllin^        ....... _   liiH            Illlllllll llilllilllll iiilllH      llllllH^                   i 1 ill I in iiiiiiii|iiii i iiiiiiiiiiiiiiiiin  I in i in in in PIT i i ..... mil i 1 1 iiiiiiiii in  i i i ...... in iiiiii in
             being intensively studied in Canada.
             Subaqueous disposal recently has been practiced by eight mines in Canada, where its use predated
             current regulations.  Three of these mines still were active aid disposing of their tailing underwater
             (two in lakes, one in the ocean) as .of 1990 (Environment Canada, 1992), as were a number of mines
          n   dsjwhere	m	the	worjd.,;	In	the	United	Staffs, regulations under the Clean Water Act (e.g., the
             effluent limitation guidelines for mills that beneficiate base and precious metal ores) effectively
	t	  prohibit subaqueous" disposal of tailings in natural water bodies (i.e., any discharge to "waters of the
iii'''!	••'!	!"  I'ji iii .U.S.'*).	The use	of subaqueous disposal in engineered structures has not been tried in the U.S.,
 i   V 11,1 ||| i gli i ii   i 111 Ik 'I 111 Jlllllllllllllllllllni' lilllllllillll11 lill illiililiillllliiWlllliillllllllllflllil Vllllllilliniiinilliiiiiiiiiiiiiiiiiiiiffli   nnnnnniiiiiijiiiiiiiiijiiiiniiiiiiiniiiniiijiiiii' 11 \	iinniiiiiiiii«i«iiii iiii uii iiii nil iiiiHii "iiinii.11,', ii ni	Hi" mi iiiiiiiii iiiiiii'iiiini,	iiiiiii, 111" mil, 'jiiniijiiiiini i 'iminii'' I'iiiiniiHiPiigii1 in wuiiF Niii'iiniii NIIIR niixii;1i,:««	    	
	'	.^oug" i«. ^ been proposed in at least one case.
            3.2.6.3     Tailings Impoundments
      i      Because mine tailings produced by the mill are usually in slurry form, disposal of slurry tailings hi
            impoundments made of local materials is the most common and economical method of disposal.
            There are four main types of slurry impoundment layouts; valley impoundments, ring dikes, in-pit
            ttBpoundments, and specially-dug pits (Ritcey, 1989).  The impoundment design choice is primarily
            .dependent upon natural topography, site conditions, and economic factors. Because costs are often
            directly related to the amount of fill material used in the dam or embankment (i.e., its size), major
            sayings can be realised by minimi-yinc the size of the dam and by marimiring the use of local
            materials, particularly the tailings themselves.  Leakage from tailings impoundments is a serious and
                                                          3-24                              September 1994
                      it  11 him  iiiiiiiii  i |iiiiiiiiiii •   i  ii    in in   in   i  ii   n    i n i    in   i in   i 11 i i  i iniii ii  i 11   i r |ln 11

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 EIA Guidelines for Mining                          .     Overview of Mining and Benefiriation

 ongoing environmental problem at many operating mines. Any leakage can transport contaminants to
 ground or surface water; uncontrolled leakage can threaten the integrity of the impoundment structure
 itself. .Increasing numbers of impoundments are lined, with or without leachate collection systems.
 Although this reduces the risk of leakage, at least in the short term, the long-term integrity of liners is
 as yet untested, particularly following mine closure when routine inspections and maintenance may be
 reduced or eliminated.

 There are two general classes of impounding structures: water-retention dams and raised
 embankments.  The choice of impounding structure is influenced by economics and site-specific
 factors including the characteristics of the mill tailings and effluent.  In general, impoundments are
 designed to move, or control die movement of, fluids both vertically and horizontally.

 Water retention dams are constructed to men* final height before the impoundment begins to receive
 tailings. The design and construction of these impoundments is similar to conventional earth dam
 technology. A typical design includes an impervious core, downstream filter and drainage zone and
 upstream riprap.  Upstream slopes are often steeper than those required for a water storage dam
 because rapid drawdown is not experienced. This impoundment type is best suited for tailings
 impoundments which must retain large water volumes. Ponds which may require this type of
 impoundment construction include those that receive large volumes of storm water runoff or store mill
 effluent not recu-culated back to the mill process.

 Raised embankments are constructed over die life of the impoundment and are initially begun as a
 starter dike constructed of native soils or borrow materials including waste rock and tailings.
 Embankment raises are constructed to keep pace with die rising elevation of die tailings and
 floodwater storage allowance.  The embankment raises may be constructed using a variety of
 materials including tailings, overburden and native soil and may be positioned downstream, upstream
 or directly on top of die starter dike.

The three most common methods used to construct tailings embankments are upstream, downstream
 and centerline.  Upstream construction begins with a starter dam constructed at die downstream toe of
die planned impoundment, with tailings discharged peripherally from die crest of die starter dam
using spigots or cyclones.  This deposition develops a dike and wide beach area composed of coarse
material which in turn becomes die foundation of die next dike.  Some type of mechanical compaction .
of die dike is typically conducted before die next stage of die dam is constructed.

As in upstream construction, downstream construction also begins with a starter dam constructed of
 compacted borrow materials; however, this starter dam may be constructed of pervious  sands and
 gravels or with predominantly silts and clays to minimize seepage through die dam   The downstream
method is so named because subsequent stages of dike construction are supported on top of die
                                            3-25                              September 1994

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	,	,,,	,	,	.QjBZfeg	gC JffiBgg sad Beneficiation        	         EIA Guidelines for Mining
                                                                      ne ctf^the^top of the dam downstream as
                               progressively ^^^  Peripheral spigotting and on-darn cycloning and spreading
        ,       i                                                                   ...... i ...... ..................... " ..... inn ...................... iS .............................. ' ................... An ........................ ............................ 3?
          ^   are common depositional methods used for downstream embankments.  .Again,  some type of '

                                                          '                          '''           '
                                               1!" 4IK^         k jii.i; ti IP * in: iiii" liiiyiiiiiiiiiliiiiiiiiii'lniiniiiiijiniiiii'' dp •iiii'ili'aiiiiiiiiii i<<«iiiiii»i iniiiiii^    "i?"' :i|ii Jini'iiiiiii aiiiii apTiijiti . Iiii* pii'iiiiiri111!;! IK , , ,! "' • PIHIIIPIIIIF '>, "m < ,i'' nlniiiiiiii'iiiiiiiiniintiiiiiiiiiiiiiiiiivi' SSi ':'" '* " 4iii:':!!iiriiiiii
           ^S^S^Snn^ffil^n	§	SiSS	IS	^^•!&8i5S!£Sm,	SSilirf.SSSSESS	SSSiSSJSS	SSSiSignS	iterf,	r,
             beach. The centerline of the embankment is maintained as fill and progressive raises are placed on
             bolh the beach and downstream face.  The tailings placed on the downstream slope are typically
             compacted to prevent shear failure.          •
                                                                                	-	•	•	"=	•	Ir	i;	"
    ii lHB!tn^                                                             	Ki lliiilV, Jllliiiil!	mj fillip          	,« iiliiHi:	hii^    	iilii liiiii S '1iii,iiiijl. liiini	iiiiili: iiniii^       	i'iiiiiil
             Other things	being	equal, it is economically advantageous to use natural depressions to contain
 -tailings. Among other advantages are reduced dam size, since the sides of the valley or other
            depression serve to contain tailings. In addition, tailings hi valleys or other natural depressions
111:1',,'' ..... "I."" ....... ' ......... present less relief for air dispersion of tailings material.      :" '     '    '  :

............................ j ............................  v?|ify impoundments (and ..... vanations^are^the ...... most ...... commgnly used nnppundments.  There are several
            variations of vaUey-type unpoundinents.  The Cross-Valley design is frequently used because it can be
            applied to almost ,any topog^b^_de|^sion ..... in ..... either ...... single or multiple form.  Laid out similarly to
            a conventional water-storage ...... dam, ........ the dam ...... fs ...... TOnsttucted ...... ajgnecting two valley walls,  confining the
            tailings in the natural valley •topography. This configuration requires the least fill material and
            consequently is favored for economic reasons.  TJhe imjwundment "is best located near fee head of Ae •
       ..................  drainage basin.to minimize flood 'inflows. Side hill diversion ditches'may be used to reduce normal •
   •      IIIIIIIIH I"1" " iiliiiiiiiiP                                         ......       '        ..... ' ..... ' .............. ...................................... — — — .~ ........ .v»»w ....... uw*.u«u
       ' ..... ",?x£ffiraa; ...... Sssi     ...... 222!, .....          ..... 52 ...... *sss*&*s* ...... 51°!?!? ......          "'
            spillways, or separate water-control dams located upstream of the impoundment.
    ..... n,,
                                           .iiiiiiiiiiiiiiniii" iiiiiin1 "i i 'in, nip,: 
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 ELA Guidelines for Mining	Overview of Mining and Beneficiation
                            V
 Where natural topographic depressions are not available, the Ring-Dike configuration may be
 appropriate. Instead of one large embankment (as in the valley design), embankments (or dikes) are
 required on all sides to contain the tailings. Construction can be similar to valley dams, with tailings,
 waste rock, and/or other native materials typically used in later phases of construction. Because of
 the length of the dike/dam, more materials are .necessary for this configuration, and material for the
 initial surrounding dikes is typically excavated from the impoundment area.

 Open-pit backfilling is also practiced, where tailings are deposited into abandoned pits or portions of
 active pits. The Pinto Valley tailings reprocessing operation, located in Arizona, uses this method to
 dispose of copper tailings. In active pits,, embankments may be necessary to keep the tailings from
 the active  area. However, since seepage from the tailings can adversely affect the stability of the pit
 walls or embankments, it is umis"ai  to see disposal in active pits. Williams (1979), for example,
 discusses a failure due to pore water pressure in the floor of a pit in Australia. Ritcey (1989) notes   .
 that the hydrogeological parameters affecting the migration of seepage and contaminants are poorly
. understood, so tailings with toxic contaminants or reactive tailings may be poor candidates for this
 type of impoundment. This method  is much less  common than the valley and ring-dike
 impoundments. Since the tailings are protected by pit walls, wind dispersion is minimized. Good
 drainage can be incorporated into the design. Many of the .failure modes common to tailings
 embankments (e.g., piping,, liquefaction) do not apply to this design. The lack of dam walls reduces
 the possibility of slope failure, but the stability of the pit slopes do  have to be checked.

 Specially dug pit impoundments are fairly unusual and involve the excavation of a pit specifically for
 the purpose of tailings disposal.   The impoundment consists of four or more cells with impermeable
 liners surrounded by an abovegrade 
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                                                                                                                 	ill	I
             Overview of Mining and Benefioafum	'	EIA Guidelines for Mining
          	""7™              :	\	:	:	:;;	:	:	:	™-	:	:	:	::	:	'	;:i	\	:;:	:	:	•	:	   .
             Tailings slurry (wet tailings and thickened tailings) is usually abrasive and highly viscous, which
             presents complications for the design, construction, operation and maintenance of tailings transport
             systems.  Slurried tailings may be transported from the mill to the tailings pond by gravity flow
             and/or pumping through open conduits or pipes.  Pipe wear is a significant problem that may be
             mitigated by the use of rubber lined steel pipes or high-density polyethylene pipe. The transport
            system may become plugged with settling solids if the minimum flow velocity is not maintained or if
5^^5:;= provisions are not made for pipe drainage during mill shutdowns.  Tailings may be discharged'from
            tbe conveyance system to any location along the impoundment perimeter; however, as discussed
                    ily, tailings (particularly sand'tailings) spigotted along raised embankments may provide  •
            additional stability.
                        Ill 111 I IIIIIIIIIH  Illllllllll  I II I  111 111111 III 111 11111II III III 111  III I  I 111111 II Illllllllllll  •  .
IIH^          .         . 11 ill 111 W II lllllllllllllllllll IN ll 111 11        • I 111 1	 11  ill 1 PI 111 1 llillllll KIIH1111W^^^   	S:                  .          "•;:> JSKtt. :, ( i ili'S s/Si!	     I
z^um&ss* Siting of tailings impoundments may be influenced by a number of factors, including location and
                              j the mill, topography, hydrogeology and catchment area,
            groundwater.  layout' of impoundments may be virtually independent of lie type of embankment used
            to	confine it.  Essentially any	of the embankment types or raising methods discussed previously may
 ,       	    be used, provided that the embankment type is compatible with site-specific conditions and the
sB^^Bfssi   characteristics of mill tailings and effluent.

i^::^;.;   3.2.6.4    Dry Tailings Disposal
                                                                      .
              *  ' <              ,            .          .   ..      ,    :	    '	     [            ,        	
            In some cases, as noted above, tailings are dewatered (thickened to 60 percent pulp density or more)
	or	jdrieg	(to	a	mogture	content	of 25	JMrcent	or .below)	priorto disposal. The efficiency^ and
            applicability of using thickened or dry tailings depends on the ore grind and concentrations of gypsum
	and clay as well as the availability of alternative methods. Except under special circumstances, these
            methods may be prohibitively expensive due to additional equipment and energy costs. However, the
            advantages include minimising seepage volumes and land needed for an impoundment or pile, and
           simultaneous tailings deposition and reclamation (Vick, 1990).

           Tailings piles are non-impounding structures that are designed for the disposal of dry tailings or
           thickened tailings. Dry tailings piles are considerably different from tailings piles created as a result
Mfi 1 (111| •II  Illlllllll                               	w^»	Illilpir       	it	                 liiBiiiSi	i	,->	i	.	,	,	
•WMlf" If of thickened tailings disposal.  Dry  tailings may be disposed of in piles that may  be constructed in a
           variety  of configurations.  These include: a valley-fill, where tailings are simply dumped to in-fill a
           valley;  side hill disposal, where tailings are disposed  on a side of a hill in a series of piles;  and level
           piles that may grow as lifts are added through out the life of the mine.  The maxjmuiri slope of
           tailings piles is determined by the physical and chemical characteristics of .the tailings.

           Thickened tailings are typically spigotted as a very viscous slurry from a permanent discharge line,
           creating a conical pile. No embankments are needed  with the exception of a small dam constructed
           down stream from the piles to intercept and collect seepage.  This method of disposal may be best
           suited for areas close to the mill and with low relief topography.
•nun iiiiiiiiiiiiiiiiiiiiini i iniii 11 ii inn iiiiiiiiiiiiiiiiini n inn in inn  iiiiiiiiiiiiiiiiiiiiini 111111111111111 nnnnnnnnnnnnnnnnnnii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii i iiiiiiiiiiiiiiiiiiiiiiii inn mi iiiiiiiiiiiiini n iiiiinnnnn nnnninn mi nninnnnnnnnn nnnnnnnnnn iniinii mi mm mm n iniiiii n ninnim nun mi nun iniiinn nn «i	Sin in i 	  	n	   	  n  	
nnnnnninnnnnnnnnn in nun inn mi i linn iniinnn i n nun in  i innnnnnninn nnnninn mi mini mini inn i minimi minim n mmmlmmmnm minium mi ninniinnnn i ninnim minimi i in mi in inn in mm in i nnnninn nniinnnninn n mini inn iinlnin ininnii nn mini mm in iiiinni n iniiiii inn inn mm mm in mm mini i  i i         II

                                                          3-28                               September 1994

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  EIA. Guidelines for Mining      	Overview of Mining and Beneficiation

  33    COMMODITY-SPECIFIC MINING AND BENEFICIATION PROCESSES

  The remainder of this section describes the mining and milling of specific metal ores, with individual
  ores discussed in separate subsections.  The ores and industry sectors discussed in the following
  subsections include gold and silver (Section 3.3.1), gold placer (3.3.2), lead-zinc (3.3.3), copper
  (3.3.4), iron (3.3.5), uranium (3.3.6), and other ores (3.3.7).  The industry sectors discussed hi more
  detail (hi Sections 3.3.1 through 3.3.6) are those representing the most mining activity hi the United
  States as of the early 1990s. Although EPA has developed effluent limitations guidelines for other
  industry sectors, there are few (and in some cases, no) actives mines for the other sectors, including
  molybdenum,  tungsten, and mercury.

 3.3.1    GOLD AND SILVER

 Historically, gold has been the principal medium of international monetary exchange, although its role
 has changed significantly to recent years.  Between 1934 and 1972, the United States monetary
 system was on a gold standard at .a fixed rate of $35 per troy ounce (a troy ounce equals 1.09714
 avoirdupois ounces, so there are 14.6 troy ounces per pound).  After leaving the gold standard hi
 1975 and allowing private ownership of the metal, the U.S. gold market grew rapidly arid the price of
 gold peaked at $850 per ounce hi January  1980.  Prices are notoriously volatile and gold prices are
 set on a number of world exchanges.  In the 1990s, gold has generally  traded hi the $300 to $400 per
 troy ounce range.

 In 1992, U.S. gold operations produced an estimated  10.3 million troy  ounces of gold from ore,
 valued at $3.6 billion. This represented an increase of 10 percent over 1991 production and nearly a
 tenfold increase over production hi the early 1980s, which averaged less than 1.5 million troy ounces
 annually. An estimated 70 percent of 1992 gold production was used for jewelry and art (including
 coinage), 23 percent for industrial purposes (primarily in the electronics industry), and 7 percent hi
 dentistry (Bureau of Mines, 1986a and 1993).

 Many new gold mines opened hi the United States throughout the  1980s (24 hi 1989), and mines
 continue to expand their production capabilities. The  United States is now the second largest gold
 producer in the world.  According to the Bureau of Mines, there, are about 200 lode gold mines hi the
 United States, primarily in the west, and a dozen or more large placer mines hi Alaska (plus hundreds
 of small commercial placer mines hi Alaska). In addition, there are hundreds or thousands of
 "recreational" lode and placer gold mines that may operate periodically (Bureau of Mines, 1993).

Gold has been mined hi virtually every State but production has been concentrated hi 15: Alaska,
Arizona, California, Colorado, Idaho, Michigan, Montana, Nevada, New Mexico,  North Carolina,
Oregon, South Carolina, South Dakota, Utah, and Washington.  According to the Bureau of Mines,
approximately 10 percent of gold production is produced as a by-product of other mining, with the
                                             3-29                              September 1994

-------
             Oyerriew of Mining and Benefication
                                                                                EIA Guidelines for Mining
             reBSainder produced at gold mines. In 1991, about 61 percent.of newly mined domestic gold from
             gold mines (or 5.7 million troy ounces) was mined in Nevada, 10 percent in California, 6 percent in
             both Montana and South Dakota, and 1 percent in Colorado, Arizona, Alaska, and Idaho.  The 25
                             Soldroducngmnes ™ 1991
                                                                    5 ...... Inhibit 3-L ................ These ..... mines ..... accounted,,,,
                                                                                           and 1993).
           Like gold, silver has been a prihcqwl medium of international monetary exchange. Silver, however,
           is aiso an important metal in many other applications.  Mine production in 1992 exceeded 57 million
                                      E°*!cea ...... <*5FJ!1 ..... PEE??! ..... °£,i?5 ...... !2!?!z ....... flowed, by Idaho (16 percent), ' -
                       .......            ......       .iZ ..... P5E5Q: .............. AJxjut ...... 50 percent of silver is used m manufacturing
           photographic products, 21 percent in electrical and electronic products, and 20 percent for a variety
           of othe!,,,?55? ....... ®iHi ...... ?lMii5,! ........ l?^3!: ............. Ii*?* 3-2 identifies ...... the ..... U.S. ....... mfne§ ...... |ha| produced the most
           silver in 1991; several of ''these have since closed, either permanently or temporarily.

           Prices for silver also peaked in the early 1980s, but have been severely depressed in recent years.
           ^ Sussed Price (generally in the range of $4 to $5 per ounce) has resulted in a significant
           «*£tfgnj5 saver mining:  almough silver is produced by over 150 U.S. mines (Bureau of Mines,
           1993), it is mined now only in conjunction with other metals, notably gold and copper.  At the
          P*?8^* 1™?* tfcere is essentially no mining in the U.S. whose primary target is silver.   This section
          focasses on gold since silver is now recovered by U.S. operations only with gold or with other metals
          that are discussed in, .separate sections.  (Although ..... BcMKt 3k2 ..... Identifies ..... :severa|,,,,,llllnes ....... whose silver is
          derived from "silver ore," in every case only the other metals recovered make recovery of silver
          *«. k*A«^ fcT "fc* i i fc>-^^ » J. *^J\J\J LW
                   deep) are called epithermal deposits, while those formed deeper are called mesothennal
                                i       -       •     „ -     ...           ;i,              b   f      ,


-------
EIA Guidelines for Mining
Overview.of Mining and Beneficiation
Exhibit 3-1. Twenty-Five Leading Gold-Producing Mines in the United States, 1991 1













Rank
1
2
2
4
' 5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
' " ' '<':* '"\ ,
Mine. >- ,
Nevada Mines Operations
Goidarike
•** 	 .»_ _. 	 ,^*_^_— ^—
HiHpmfiT CagyoB
lends Canyon (Bnfidd Bell)
Snxfy Va3eyComaoa€pea&aB
Hotncstflifff
McCoy and Cove
Mclaughlin
Chimney Creek
Fortitude and Surprise
Bulldog
Mesqufte
Getchell
Sleeper
_annon
Ridgeway
Tamestown
Paradise Peak
Rabbit Creek
iarney's Canyon
Continental
Zonman-Landusky
3olden Sunlight
Vind Mountain
Fbley Ridge & Annie Creek
County and State
EQcD and Eureka UV
EateSaSiF
SaltLaieUT
HkoNV
N»eWV
LzwKoeeSD
Lander NV
NapaCA .
HumboldtNV
Lander NV
HyeNV
LnperialCA
HumboldtNV
HumboldtNV
ChelanWA
FairfieldSC
fuolumne CA
NyeNV
HumboldtNV.
Salt Lake City UT
Silver Bow MT
Phillips MT
efrerson MT
WashoeNV
Lawrence SD
Oponrtor
Nfiwsoflt Gold Co.
Barrick Mercury Gold Mines Inc.
Kennecott-Utah Copper Corp:
Freeport-McMoran Gold Co.
Round Mountain Gold Corp.
Hmffcstflkc Mining Co
Ecbo Bay Mining Co.
Homestake Mining Co.
Gold Fields Mining Co.
Battle Mountain Gold Co.
Bond Gold, Bullfrog, Inc.
Goldfields Mining Co.
FMG Lie.
Amax Gold Inc.
Asamera Minerals (U.S.) Inc.
Ridgeway Mining Co.
Sonora Mining Corp.
FMC Gold Co.
Rabbit Creek Mining Inc.
Kennecott Corp.
Montana Resources
Pegasus Gold Inc.
Golden Sunlight Mines Inc.
Amax Gold Inc.
Wharf Resources
Source of
Gold
Gold Ore
Gold Ore
Copper Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Gold Ore
Copper Ore
Gold Ore
Gold Ore.
Gold Ore
Gold Ore
Source: Bureau of Mines, 1992.

1



                                       3-31
                  September 1994

-------
         Overview of Mining and Benefidation
EIA Guidelines for Mining
Exhibit 3-2. Twenty-Five Leading Silver-Producing Mines in the United States, 1991
I
i
Rank
1
2
3
4
S
6
7
S
9
' 10
11
'12
13
14
15
16
17
18
19
20
21
22
23
24
25
!:-:?z.v-'ite^$$?'&.
McCoy and Cove
Greens Creek
Rochester
Rrnoham CaTWffll

Tray
Red Dog
Sunshine
Lucky Friday
DeLanar
Paradise Peak
Galena
Montana Tunnels
Mission Complex
WhJtePine
^andclaria

Coodoeotal
Ray Unit
Demon-Rawhide
j^nrtman-I^fxty^fcy
kforcnci
Bagdad
San Manuel
Baale Mountain Complex
Chino
Pinto Valley
s--vii."'::, '-:' . U *
• COiiilty MDu Stiklt
Lander NV
Admiralty Island AK
PershingNV
Salt Lake UT
Lincoln MT
NW Arctic AK
SboshonelD
ShoshonelD
OwybeelD
NyeNV
ShoshonelD
Jefferson MT
Puna AZ
OotbnogonMT
Mineral NV
Silver Bow MT
Final AZ
Mineral AZ
Phillips MT
GreenleeAZ
YavapaiAZ
PinalAZ .
Lander NV
Grand MM
GflaAZ
. .* ,: f\nm*ilt ii • ' ,'"'•'•• '
• ^ f uptnuar •, .' •'
Echo Bay Mining Co.
Greens Creek Mining Co.
Coeur Rochester Inc.
Kermecott-Utah Copper Co. •
ASARCOInc.
Cominco Alaska
Sunshine Mining Co.
Hecla Mining Co.
NERCO De-Lamar Co.
FMC Gold Co.
ASARCOInc.
Montana Tunnels Mining Inc.
ASARCOInc.
Copper Range Co.
NERCO Metals Inc.
Montana Resources Inc.
ASARCOInc.
Kennecott Rawhide Mining Co.
Pegasus Gold Inc.
Phelps Dodge Corp.
Cyprus Bagdad Copper Co.
Magma Copper Co. '•
Battle Mountain Gold Co.
Phelps Dodge Corp.
Magma Copper Co.
Source: Bureau of Mines, 1992.
Source of Silver
Gold Ore
Zinc Ore
Silver Ore
Copper Ore
Copper ore
Zinc Ore
Silver Ore
Lead-Zinc Ore
Gold Ore .
Gold ore
Silver Ore
Zinc Ore
Copper Ore
Copper ore
Silver Ore '
•-Opper Ore '
Copper ore
Gold Ore
Gold ore
Copper Ore
-opper ore
Copper ore
Gold Ore
Copper Ore •
Copper ore








Ililllllllllllllllll
                                                  3-32
        September 1994

-------
  EIA Guidelines for Mining	    Overview of Mining and Benefication

  deposits. Combinations of the various types of hydrothennal systems in various host rocks create
  variations in deposit morphology, grade ranges (variation in gold content), and wall rock alteration.
  Deposit morphology ranges in a continuum from veins several feet thick and hundreds to thousands of
  feet in vertical and lateral dimensions (formed by mineral precipitation in voids'hi the host rock) to
  disseminated mineralization (essentially micro veinlets) pervading through the host rock in irregular
. pods up to several hundred feet in dimension.

  Gold deposits may be categorized based on similarities in geologic environment and generic
  hydrothennal factors. Recent data show that the 25 largest gold producing mines in the U.S. may be
  grouped into four types:  sediment-hosted disseminated gold (examples are the Goldstrike and Gold
  Quarry mines), volcanic-hosted epithennal deposits (McLaughlin, Chimney Creek), porphyry copper-
  related deposits (Bingham Canyon), and greenstone gold-quartz vein deposits (Homestake).  (Bureau
 of Mines, 1990c).

 .Grades range in all deposit types from subeconomic margins to high-grade ores.  The term "high
 grade" varies with mining methods but usually refers to ores greater than 0.1 or 0.2 oz/t. Likewise,
 average  deposit grades are economic distinctions.  Deposits requiring high-cost mining and milling
 methods may require bulk averages of 0.25 oz/t or more, at 0.15 or higher cutoffe. Those deposits
 that are. amenable to the lowest-cost mining and milling methods may average 0.03 to 0.04 oz/t or
 less with an ore-to-waste separation grade of about 0.01 oz/t.

 The mineral content or assemblage of a deposit is the result of reactions between hydrothennal
 solutions and the wall rock, influenced by wall rock chemistry, solution chemistry, temperature, and
 pressure. Most gold ores contain some amount of sulfur-bearing minerals;  carbonate deposits may
 also contain carbonaceous material.  The weathering environment affecting  the ore body following
 deposition is determined mainly by the location of the water table (either present or past) in relation
 to the deposit.  Ores above the water table, hi the vadose or unsaturated zone, will tend to be
 oxidized (referred to as "oxide ores"), while ores below the water table will usually be unoxidized
 (referred to as "sulfide ores").

 Gold ores may contain varying amounts of arsenic, antimony, mercury, thallium, sulfur, base metal
sulfides,  other precious metals, and sulfosalts.  The amount of these constituents depends on the
nature of the deposit and the amount of weathering that has occurred.  Subsequent alteration of the
ore by oxidation influences both gold recovery and the byproducts of extracting the ore.  Sulfide
minerals  oxidize to form either oxides or sulfosalt minerals.  Leaching of sulfides or other minerals
may  occur in association with oxidation. Sulfide ores retain their original composition. Zones of
secondary enrichment may form at the oxidized/unoxidized interface.
                                             3-33                              September 1994

-------
   •IIH
            Overview of Mining and Benefidation
                                                                                EIA Guidelines for Mining
       IK in I in HI 11 ill in
           The minerals found in gold ores, and elements associated with them, vary with the type of ore.
           Sulfide ores contain varying amounts of native gold and silica (SiO^, as well as sulfur-bearing
           minerals, including, but not limited to, sphalerite (ZnS),  chalcopyrite (CuFeSj), cinnabar (HgS),
           galena (PbS), pyrite (FejjS), sylvinate ([Au,Ag]Te2), realgar (AsS), arsenopyrite (FeAsS), ellisite
           (TljAsSj), and other thallium-arsenic aniimony-mercury-bearing sulfides and sulfosalt minerals.
           Oxide ores may contain varying amounts of these minerals, as well as silica (SiOj), limonite
           (FeO-OH-nH2O),  calcfte (CaCOa), clay minerals, and iron oxides (Hurlbut and Klein, 1977).
           The mineral assemblage of the ore deposit is an important factor in the beneficiation method to be
           used. In general, the percent recovery of gold from sulfide ores using various cyanidation techniques
   III 11! 111111||  iiiijin i nil i n n i  iiiini minimi in iiiiiini i nnnnnniiiiiiiiini nniiiiiiiiiiini i in mi iiiiiini mi n iiiini n n in i inn i n mi inn iiiini iiiiinn in i iiiiini mi in iiiini n i inn 111 n in n n inn i inn mi iiiiini iiiini in inn i iiiiini 111 in in i mi mi 11 in i in i nil 11 in iiiiini n in n 11 in i in in in i iiiiini in i in iiiiiiiiini in n i n i iiiini nniiiiiiiiiini inn n nil i n iiiiiini iiiini n i in n in nil in nuii t nnn	:a \ta\\n~	i
           is lower and more costly than from oxide ores.  Recovery is reduced because the cyanide solution
           also reacts with constituents  such as sulfides in addition to gold.  Increasingly, sulfide ores may be
         	oxidized in roasters or autoclaves.  This is the result both of the development of more cost-effective
           oxidation techniques and  of the fact that oxide ores are •becoming increasingly scarce (Weiss, 1985).
          3*3.1.2     Mining
          Gold ore may be mined by either surface or underground techniques. Mining methods are selected
          based, on maxfrmm^ ore recovery, efficiency, economy, and the character of the ore body (including
[[[ dig, size, shape,'and strength) (Whiteway, 1990). ........ With notableexceptions (e.gT, ..... the Homestake
          mine), most gold ore in the United States is mined using surface mining techniques hi open-pit mines.
          This is primarily because of economic factors related to mining large-volume, low-grade ores and the
[[[ improvement of cyanide leaching techniques. In 1988, a total of 160 million short torn of crude ore
          (97.8 'percent of the total) was handled at surface lode mines. " In contrast,' 'underground mines mined
          onlySGS ..... miiium ..... Short ..... tons ...... (25 .....        ......       ......                         .....   ...... ----—    ........ -- .......
                                                          oMmes, 199

i II i Illlllllll jitf      I 111 1 1 |||||||||||||l|i|||||||i^
          amounts of crude ore, waste, and marketable product generated by surface, underground, and placer
          operations in 1988.

Exhibit 3-3, Materials Handled at

•'•' Mrterar -••''••'••»
Surface and Unc

lerground Gold Mines, 1988
''•<•'••."/•>-•. •-••''.•.-••^: ' •' •'• Lode-' •••'• •••: •<•' 	 '
•*•• Surface v =
Underground
Total
Placer
Material handled (1,000 short tons):
Total
Crude Ore
Waste
Marketable Product
(1,000 Troy oz.)
553,000
160,000
394,000
5,250
4,890
3,560
1,340
241
558,000
163,560
395,000
5,490
32,900
15,000
17,900
153
Source: EPA, compiled from Bureau of Mines, 1990b.


-------
 EIA Guidelines, for Milling	       Overview of Mining and Beneficiation

. The quantity and composition of waste rock generated at mines vary greatly by site.  This material
 can contain either oxides or sulfides (or, more likely, both), depending on the composition of the ore
 body.  Constituents include mercury, arsenic, bismuth, antimony, and thallium, and other heavy
 metals.  These may occur as oxides, carbonates, and sulfides with varying degrees of solubility.
 Sulfur-bearing minerals, such as pyrite and pyrrhotite, can oxidize to form sulfuric acid (Bureau of
 Mines, 1984).  Factors that influence acid generation by sulfide wastes include the availability of
 oxygen and water; the presence and availability of acid-generating and/or neutralizing minerals in the
                               • •                              \
 rock; and the design of the disposal unit.  Overburden and waste rock are generally disposed of in
unlined piles known as mine rock dumps or waste rock dumps (occasionally, they can be called "low-
grade ore"  or "subore" stockpiles).  Waste dumps are generally unsaturated. Waste rock also is used
in constructing tailings dams, roads, and for other onsite purposes.  Waste rock with high sulfide
content and sufficient moisture  content, and without adequate neutralization potential or other controls
in the dump itself (e.g., encapsulation or segregation of sulfide material within the dump), has led to
significant problems associated with acid drainage, both from waste  rock dumps and from roads and
other onsite construction made of sulfide waste rock.

Mine water consists of water that collects in mine workings, both surface and underground, as a
result of inflow from rain or surface water, and groundwater seepage.  Mine water may be used and
recycled in  the beneficiation circuit, pumped to tailings impoundments,  or discharged to surface water
under an NPDES permit.  During the life of the mine, if necessary,  water is pumped to keep the mine
dry and allow access to the ore body. This water may be pumped from sumps within the mine  or
from interceptor wells surrounding the mine. Interceptor wells are used to withdraw groundwater and
create a cone of depression in the water table around the mine, thus reducing groundwater inflow.
Surface water is most often controlled using engineering techniques to prevent water from flowing
into the mine.

The quantity and chemical composition of mine water generated at mines vary by site. The chemistry
of mine water is dependent on the geochemistry of the ore body and  surrounding area. After the
mine is closed and pumping stops, the potential exists for mines to fill with water. Water exposed to
sulfur-bearing minerals in an oxidizing environment, such as open pits or underground workings, may
acidify, and mobilize metals in the rock matrix. In contrast, flooding of some mine workings may, in
some unusual situations, serve to slow or stop acidification by reducing or eliminating the source of
oxygen.

In addition to wastes generated as part of gold mining and beneficiation, facilities also store and use a
variety of chemicals required by the mine and mill operations.  Exhibit 3-4 presents a list of
chemicals used at gold mines, compiled from data collected by the National Institute for Occupational
Safety and Health (NIOSH, 1990).
                                             3-25                              September 1994

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         Overview of Mining and Benefidation
                                                                      EIA Guidelines for Mining


Exhibit 3-4. Chemicals Stored and Used at Gold Mines j










Acetic Acid
Acetous
Acetylene
Ammonia .
Argon
Asbestos
Butyl Acetate
Calcium Carbonate
Calcium Oxide '
Carbon Dioxide
Chlorine
Coal ,
Copper
Diatomaceous Earth '
Didikttodifluoromethane
Diisobutyl Ketone
Ethauol
Fluoride
Graphite
Hexone
Hydrogen Bromide
Hydrogen Chloride
Hydrogen Peroxide
Iron Oxide Fume
Kerosene
Lead
Lead Nitrate
Litharge
Mercuric Chloride
Mercury
Methyl Acetylene-
Propadiene Mixture
Methyl Alcohol
Methyl Chloroform
Mineral Oil
Molybdenum •
Nitric Acid
Nitrogen
Nitrous Oxide
Oxalic Acid
Phosphoric Acid
Portland Cement '
Potassium Cyanide
Propane
Pyridine
Sucrose
Silica, Sand
Silica, Crystalline
Silver
Silver Nitrate
Sodium Cyanide
Sodium Hydroxide
Stoddard Solvent
Sulfuric Acid
Tin
Vanadium Pentoxide
Xylene
2-Butanone
Diesel Fuel No. 1
Source: National Institute for Occupational Safety and Health, 1990.





1
1
1
1


        Surface Mining                             '
  iiiiiiiiiiiii!	         _           •   ,	Ntvjt;EHK3Mi';ii4,it u	is	K*,a	IE	si,	»*,i,i;iisii<:flw:	ax	SMtjHir.*	         •	            .•	'	ii
        Surface mining methods associated with the extraction of gold include open-pit and placer (including
        dredging, which is often considered separately). Placer mining is used to mine and concentrate gold
        from alluvial sand and gravels and is described hi Section 3.3.2.
       Surface mining of gold is generally more economical than underground methods, especially in cases
    	wfaen_	to oretojjjr	bong mnied	is	large	and	the	degth	of ovobmriencoye^'te deposit is limited.
    	Tne primary advantage of suSce inining is the ability to move large amounts'of material at a
       relatively low cost, in con^arison.withunderground operations.
 ii in •
I ................... | ..................................
 IK ip 11|H  ..... l|i||i ii ilillllll'ill illlllllllllllllllill             .                             .....    .                 - ....... ;;U '.'-Upl
The predominant surface mining method used to extract gold ore is open-pit. Surface mining
practices follow a basic mining cycle of drilling, blasting, and mucking.  The depth to which an ore
ftS .....        ......          ...... 22 ..... 22 .....          ..... SE ..... SSSlrfj^^ ....... nature ..... pfjfae ..... overburden, and
the stripping ratio. The stripping ratio is .the amount of overburden and waste rock that must be
      removed for each unit of crude ore mined and varies with the mine site and the ore being mined
                                                      I                     II          °   :
           III               '   I                   "I          II       i I        I   '        '
      Stripping ratios can range up to 5 to 10 tons of overburden and waste rock per ton of ore or higher at
      °Pen"Pit mines; it usually ranges around 1 to 3 tons per ton.  These materials become wastes that
      must be disposed of, primarily in waste rock dumps.  Because ore grades in mined material are
                                  °    oncenn      below the "cut-off grade (i.e., the 'grade at

: ....... inns is, often referred to as
                                 ££2ffi5H^B$ JHST ** stockpiled separately from other waste rock— this
                                    -                                         '
                                      or «iovf_graijs ore
                                                                           me
            .          C*?mB*Vfith ±e price of gold' tfn* -leading to more or less waste rock being disposed
~™" ....... •-' ....... iS"fhe stripping ratio changes.
                                                                                    September 1994

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  EIA Guidelines for Mining                                Overview of Mining and Beneficiation

  Underground Mining

  Underground mining operations use various mining methods, including caving, stoping, and room and
  pillar. In general, underground mining involves sinking a shaft or driving a drift near the ore body to
  be mined and extending horizontal passages (levels) from the main shaft at various depths to the ore.
  Mine development rock is removed, while sinking shafts, adits, drifts, and cross-cuts, to access and
  exploit the ore body.  From deep mines, broken ore (or muck) is removed from the mine either
  through shaft conveyances or chutes and hoisted in skips (elevators).  From shallow mines, ore may
  be removed by train or conveyor belt. Waste rock, mine development rock, or mill tailings may be
  returned to the mine to be used as fill for mined-out areas (EPA, Office of Water, 1982).  The ratio
  of waste rock to ore is much lower at underground mines than.at surface mines, reflecting the higher
  cost of underground mining. Because of the higher costs, underground mining is most suitable for
  relatively higher-grade ores. This in turn reduces the amount of beneficiation wastes (i.e., tailings)
 generated (and disposed) per troy ounce of gold produced.                         .

. In Situ Mining

 In situ leaching, although increasingly common hi the copper industry, is only an experimental
 procedure in the gold industry and is not used in commercial operations. It involves blasting an
 underground deposit in place to fracture the ore and make it permeable enough to leach.
 Subsequently, 20 to 25 percent of the broken ore is removed from the mine to provide "swell" space
 for leaching activities. In buried ore bodies, cyanide solution is then injected through a well into the
 fractured ore zone.  At surface ore bodies, the solution can simply be sprayed over the deposit.
 Recovery wells are used to collect the gold-cyanide solution after it percolates through the ore.
 Groundwater and surface water concerns are commonly raised in discussions of potential in situ
 operations.  In situ leaching has only been tested at the Ajax Mine near Victor, Colorado (Bureau of
 Mines, 1984).

 3.3.1.3    Beneficiation

 Four main techniques are used to beneficiate gold ore: cyanidation, flotation, amalgamation, and
 gravity concentration. Exhibit 3-5 illustrates the common methods used to beneficiate gold. The
 method used at a given operation depends on the characteristics of the ore and economic
 considerations (Bureau of Mines, 1984).  Each of the four techniques is described below.  Base-metal
 flotation is described only briefly, since gold is produced only as a byproduct at these operations.
 Amalgamation also is discussed only briefly, since this method is primarily of historic significance  in
 the United States.  Gravity concentration methods are generally used only in placer-type operations
 and are discussed in a separate section (Section 3.3.2). Cyanidation operations are by far the most
 common, and are described in more detail below. The two basic types of cyanidation operations,
 heap leaching and tank leaching, are described separately.
                                             3.37                              September 1994

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                  Mining and Benefidation
                                                                       EIA Guidelines for Mining

                         Exhibit 3-5.  Gold Mining and Benefication Overview
                                    (Adapted from various sources)
                                         (Open Pa or UndMtpound)
                          CutMntaPuto
                                         Gold Adoption
                               Ekfton (stripping gold
                               warn aetivtiKj cuton)
		i	i	u	,	i	

-------
 EIA Guidelines for Mining
Overview of Mining and Beneficiation
Exhibit 3-6 presents a comparison of gold ore treated and gold product produced by the various
beneficiation methods in 1991.  As can be seen, cyanidation and direct processing (smelting of
precious metals recovered as a by-product from base metal mining) were used to produce 89 percent
and 10 percent of all domestic recovered lode gold, respectively.  Placer mining accounted for 1
percent of the total gold produced. Amalgamation was used to beneficiate much less than 1 percent
of all lode gold in 1986, the last year for which complete data were reported (Bureau of Mines,
1990a).                    .
1
Exhibit 3-6. Gold Ore Treated and Gold Produced, By Beneficiation Method, 1991
, -- -- - ^ , - - '' -\ /sr -

Beneficiation Method
Cyanidation (All)
Heap Leaching
Tajik Leaching •
ATHJJI gatnsil iftn^
Smelting (ore and concentrates)^
Total Lode
Placer (gravity)
Gold Ore Treated
Percent
51
36
14
0.5
49
100
100
Source: Bureau of Mines, 1992.
Notes: .
Due to rounding and unit conversions, totals may not i
a Values for amalgamation axe for 1986 productio
was available.
b^tneltinff tif has£ metal nnss and ^mcmtrates m
information is not available specifically for flota
suggested that these production figures approxin
industry.
Short Tons
(OOOs)
227,271
159,985
67,285
0.9
221,507
. 449,920
5,500,000
cubic meters
Gold Produced
Percent
89
33
56
0.3
10
99
1 .
Troy •oZi-x'-;'« ;-
8,235,820
3,037,084
5,198,736
33,694
909,736
9,227,187
92,851
match exactly.
n, the last year for which complete information
ainly copper and lead ores. Production
tion, but Bureau of Mines personnel have
iate byproduct gold production by the base metal

By-Product Gold (Rotation)

As described above, flotation is a technique hi which particles of a single mineral or group of
minerals are made to adhere, by the addition of reagents, preferentially to air bubbles (EPA, Office of
Water, 1982). This technique is chiefly used on base metal ore that is finely disseminated and
generally contains extremely small quantities of gold hi association with the base metals.  Gold is
recovered as a byproduct of the base metal recovery (for example, recovered from electrowinning
sludges or slimes).
                                             3-39
                     September 1994

-------
                   of Miffing and Beneficiation ..	       EIA Guidelines for Mining
        ''255	,g	SSSsI	and	SSjSi	py size m preparation for flotation.  The ore is then slurried with chemical
                 2.52S	252	22E	JSS^^^^S^^^	—S^F5' iactivat°rs, arid depressants.  In a-
        iJlSS*:*!	S*^0,^,.!!?*	°Hslu557 ?®*,*??i§Fms *** ™!?^ j£a conditional cell so the reagents coat the
        ?-Sr|p	mtoenl.  Thei;con£tion^ slurry is pumped to a flotation cell,, and air is injected.  Air bubbles
              SJO	tie	rg|en£s	and	carry	the	target	mineral i to	the	surface,	away from the remaining gangue,
              ?!55!!0,!!:	Ifi	Ife	§2§S?°J!	.tSSl!!!?116' ^ target mineral is not necessarily the precious metal or
              SlES:  Dependmg on the specific gravity and the reagents used, the values may be recovered
                 top or bottom of .the flotation cell.
         ~	i	"" <                                                           i
         In general, mere would be little or no incremental environmental concerns as a result of byproduct
        "=*'*	==	A=;	±=55=rj^^	would be	related	to""the	^g"'^^	^r^—	—^

       Wastes generated as a result of amalgamation activities consist of gangue in the form of coarse- and
       fine-framed particles and a liquid mill water component in the form of a slurry. The constituents of
       ^ ^K ..... — ..... ^^£ ..... !°, ....... *25 ...... f0.^ ..... 2 ..... ,$£ ...... 25 ..... !Slv. ...... fi£ ..... £5X5!) Plus any mercury lost during
       amalgamation. TMs ^^d can then be" i^^ed to. a tailings' impoundment, , In the past, some U.S.
       operations (as well as current operations in other parts of the world) simply directed the tailings to
       nearby streams or valleys.  In some areas, the amount of mercury lost during historic mining has
           amalgamation operations, metallic gold is wetted with mercury to form a solution of gold in
        mercury, referred to as an amalgam.  This method of beneficiation is most effective on loose or free
        coarse gold particles with clean surfaces (EPA, 1982). Because of its high surface tension, mercury
        does not penetrate into small crevices of ore particles, so the ore generally must be crushed finely
............ | [[[ ^lilSS05* *e*aM material. Use of mis.method of gold beneficiation has been greatly
|iP M, 'HRpSnn -ii« ..... « ........ Si iSSiSF?* past because of its high costs, inefficiency in large-scale
        op"^00** and the scarcity of ores amenable only to this technique. In addition, environmental
        concerns related to mercury contamination have contributed to its limited use. It is stili used in other
 J     P3"5 °f the world, particularly remote areas such as the upper Amazon, where its suitability for
       small-scale operations and limited environmental concerns have not restricted its use.
                                                                                  i
I  I 111 I III I I 111 111  I II  Illl 111 II 111 II ll|lllllll  illlH^^^^   Illlllilllllll 111  I III I I   I III III III 111 I 111  Illl III I 111 111 I I III 111 I III II I 1111 111 111 I Illlllllllll 111 111 I Illl III I I 11111 III III II 111 I I ill 111 II II  1 1 111 II I I 111 III I  I  111 III  III 11 111 11 II
       Ore preparation consists of grinding, washing, and/or floating the ore. The ore is then fed into a ball
       mffl along with mercury to form an amalgam. The amalgam is then passed over a series of copper
       plates where ifcollects. When fuUy loaded with amalgam, the plate is removed and the amalgam is
       scraped off. Upon heating the hardened amalgam in a retort furnace, the mercury is vaporized and
       thc S°Id material remains.  The mercury driven off by heating is captured, condensed, and reused.
       Alternatively, ..holdjutejiitnc acid may be applied to the  amalgam, tlissolving the mercury and
       lw*v% ....... —,i?—. ..... 25S?^ ............... ^E^IEE!!!0,?. ...... i!55 ....... SS^^SS? ..... .been ..... used ....... m conjunction with other

-------
  EIA Guidelines for Mining                                Overview of Mining and Beneficfation

  been significant, and has led to widespread mercury contamination.  . For example, modem placer
  operations in California have recovered substantial amounts of mercury from stream sediments
  contaminated by past amalgamation operations.

  Cyanidation                                    •

  As noted previously, the predominant methods used in the U.S. and the developed world to    ~
  beneficiate gold ore involve cyanidation. This technique uses solutions of sodium or potassium
  cyanide as lixiviants (leaching agents) to recover precious metals (including gold and silver) from the
  ore.  Cyanide heap leaching is a relatively inexpensive method of recovering gold from lower-grade
  ores while tank leaching is used for higher grade ore.  Although other lixiviants are currently being
  tested, none are known to be used in commercial operations.  Alternative lixiviants include
  malononitrile, bromine, urea, and copper-catalyzed thiosulfate (Bureau of Mines,  1985; Bureau of
  Mines, undated(a)).

. .The cyanidation-carbbn adsorption processes most commonly used involve four steps:  leaching,
 loading, elution, and recovery (van Zyl et aL, 1988) (see Exhibit 3-7). In leaching, the cyanide
 reacts with the ore to liberate gold material and form a cyanide-gold complex in an aqueous solution.
 Precious metal values in this solution are men loaded onto activated carbon by adsorption. When the
 loading is complete, the.values are eluted, or desorbed from the carbon, and recovered by
 electrowinning or zinc precipitation prior to smelting.  An alternative to cyanidation/carbon adsorption
 is cyanidation/zinc precipitation.  The cyanidation-zinc precipitation technique also involves four
 steps: leaching, clarification, deaeration, and precipitation.  The precipitate (a solid) is smelted
 directly.

 Cyanidation is best suited to fine-gram gold in disseminated deposits. Cyanidation techniques used in
 the gold industry today include:

      •   Heap or valley fill leaching followed by carbon adsorption (carbon-in-column, or CIC,
          adsorption)

      •   Carbon-in-pulp (CIP) operations, where the ore pulp is leached in an initial set of tanks
          with carbon adsorption occurring in a second set of tanks

      •   Carbon-in-Leach (CIL) operations, where leaching and carbon recovery of the gold values
          occur simultaneously in the same set of tanks

      •   Cyanide leaching in heaps or tanks (CIP) followed by zinc precipitation (the Merrill-Crowe
          process).
                                              3-41                               September 1994

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                	'	j	I	
                   1 I
            Orerriew of Mining and Beneficiation
                                                     EIA Guidelines for Mining
                           ExfaibitS-7.  Steps for Gold Recovery Using Carbon Adsorption
                                          (Adapted from various sources)
               LEApHfNQ
                                                     ORE
HEAP OR VALLEY
   LEACHING
                                                                        CRUSHING, GRINDING.
                                                                           BENEFICATION.
                                                                           CALCINATION
IH^^^^^^^
IIIIIIIIH^ ....... Ill 111:.
                   HlltM^^^^^^^^^^

                       	3-42
                                                                                     September 1994


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 EIA. Guidelines for Mining                               Overview of Mining and Beneficiation

 As noted previously, in situ cyanide leaching to recover gold directly from ore bodies is a subject of
 research by the Bureau, of Mines and others, but is not used commercially at this time.  Other
 methods to recover the precious metal from the cyanide solution following leaching include solvent
 extraction and direct electrowinning; these methods are not common in the industry and are not
 discussed here.

 Heap or valley fill leaching is generally used to beneficiate ores containing an average of less than
 0.04 troy ounces- of gold per ton of ore.  QP and QL techniques, commonly referred to as tank or
 vat methods, are generally used to beneficiate ores averaging more than 0.04 oz/t. Gold beneficiation
 cut-off values are dependent on many factors, including .the price of gold and an operation's ability to
 recover the precious metal (van Zyl et ah, 1988). At many heap leach operations, the lower cut-off
 grade is around 0.01 to 0.02 oz/t.

 The sections below describe gold beneficiation using the various cyanidation techniques.  The first
 subsection describes ore preparation that may take place before cyanidation. This is followed by
 sections that describe heap leaching and tank leaching, respectively, with carbon adsorption and zinc
 precipitation discussed in the heap leaching section.  In each section, the discussion focusses on the
 operations, the waste generated, and the major environmental concerns during and after operations.

 Ore Preparation

Depending on the type of ore (sulfide or oxide), the gold concentration in the ore, and other factors,
the mine operator may prepare the  ore by crushing, grinding, and/or oxidation (roasting, autoclaving,
or bio-oxidation) prior to cyanidation or flotation. Crushing and grinding are described briefly.
below, as is oxidation.

Crushing and Grinding. In most cases, ore is prepared for leaching or flotation by crushing and/or
grinding.  These operations produce relatively uniformly sized particles by crushing, grinding, and
wet or dry classification. Factors that determine the degree of ore preparation include the gold
concentration and the mineralogy and hardness of the ore, the mill's capacity, the next planned step  in
beneficiation, and general facility economics.  Run-of-mine ores with very low gold concentrations
may be sent directly for heap leaching with no prior crushing or classification.

Milling begins when ore material from the mine is reduced in particle size by crushing and/or
grinding.  A primary crusher, such as a jaw type, is used to reduce ore into particles less than ISO
millimeters (=  6 inches) in diameter. Generally, crushing continues using  a cone crusher and an
internal sizing screen until the  ore is less than 19 mm (= 3/4 inch).  Crushing in jaw and cone
crushers is a dry process, with water spray applied only to control dust.
                                             3-43                              September 1994

-------
                                                              lull ill1 illl'illlllH                                 	ililill 111 1111 III Illillllllllillllllll
             Orerriew of Mining and Benefitiation
                                                  EIA Guidelines for Mining
             From die cone crusher, ore to be leached in tanks is fed to the grinding circuit where milling
             continues in the presence of water, often with cyanide added to begin the ieadung~process (ore to be
' ....... "n .......... " ': ...... "u .......... "" " leached in heaps or valley fills ....... is x&^m'ihe^^                           ............... —  — . ......
             form a slurry containing 35 to 50 percent solids. Grinding then occurs hi ball or rod rniis to further
             reduce the ore particle size. In some cases, ore and water are fed directly into an autogenous mill
             (where the hard ore itself serves the grinding medium) or a semiautogenous mill (where the ore
          •  supplemented by large steel balls are the grinding media).  Between each grinding unit operation, .
[[[ hydrocyclones ...... are used to classify coarse and. fine particles, with coarse particles returned to the
            circuit for further size reduction and fine particles continuing through the process. Milled ore is in
            the form of a slurry, which is  pumped to the next unit operation (Weiss, 1985; Stanford, 1987).
            Fugitive dust generated during crushing and grinding activities is usually controlled by water sprays,
            although there may be other ah* pollution control devices whose blowdown streams may be  .
[[[ recirculated into the beneficiation circuit.
            QxidationjofjSulfides (Roasting. Autoclaving. and Bio-Oxidation).  Beneficiation of sulfide ores may
  •          include oxidation of sulfide minerals and carbonaceous material by roasting, autoclaving, bio-   •
HSSS'jS oxidation, ....... or ..... chlorfnatipn ..... (chlorination is not commonly used because of the high equipment •
[[[ I ................ maintenance costs caused by the corrosive nature ..... of the oxidizing agent). Roasting ...... involves ....... heating
            sulfide ores in ah* to convert them to oxide ores amenable to cyanidation. In effect, roasting oxidizes
            the sulfur in the ore, generating sulfur dioxide that can be captured and converted into sulfuric acid.
            Roasting temperatures depend on the mineralogy of the ore, but range as high as several hundred
•'S,™i ™i degrees ....... Cdsjus. .............. Roasting ..... of ores ...... that ...... contain ..... carbonaceoj^ material ....... oxidizes ....... the ...... carbon ..... that
            otherwise interferes with leaching and reduces gold 'recovery efficiency.  Autoclaving (pressure
            oxidation) ....... is ...... a relatively ...... new ...... technique that ogerates at lower ternperatures than roasting.
............. , .............. , ....... ,,, ..... „ ............... ............ '_, ...... , .................. Autoclaving uses pressurized steam to start the reaction and oxygen to oxidize sulfur-bearing •
            minerals. ............... Heat ..... released ..... from ..... the ..... oxidation .of sulfur then sustains the reaction.  Roasting and
                          ..... !El9lll!!lllll!llllll!!l!!l!!1ll!;1!ll!!!!!lllllll!ll?f       ....... !ir ...... ilElllKllBlltlinillllllElllllilinilTirlllii'll'l ......... 'Till1!!!!!!!!1!:!"!!! ...... !l!!l!!llilllllll!l!!!!lill!!!1l||ll>vll!:i!!!!!!!!!l!!l!tl!l ..... III! ....... I'!"!!'!"! ......... llffllliinil'S'llKSISIIIIfJ!]         ..... !JI|l1i;ll!!!!!l!l!l!l!!!!l' !I!9"!II!I!I"?SS'I ,r .................... ......... ...........
                       are being used ..... morej^entl  in the USasibe technologic become more cost- •
    •       ......
                                                bacteria to oxidize the sulfar-bearing minerals.  'This technique
           is currently used on an experimental basis at the Congress Gold Property in fanaria and at the
           Homcstake ....... Tonkin ....... Springs property in Nevada. The bacteria used in this technique are naturally
Illlllllllllllli lil!!!1l1J|il3|||j||||||ii|'i|||l||l:!||||l||||||F Ill^                                   ...... ''" ....... '"' ....... :l'"' ..... lll!l!'' ............ i!1'!11!!!':*111!!!1111!1*!!1!1111!!!1!!!1"'!'!! ...... i!1"!1 ''!' 1 ..... iii"ft!il*i|i«|||!|i!!!ii'l»iii| ........ '!iliii|n|i|»!i!iii|i| ..... iipi'iiniillii'.iiiiiiiiiiiniH'ii ...... |iii:!«||||||i«||||||i|iil!! ...... ip ..... IliplwiPPI^lllliiniiiiii''!'!'!!!''!!!^!!!!!'!!!;.!!!''!!!!!! .............. run .............. I'll ..... I!1!"1! ............. **i •'!'"'" •• r -:!
                            ically include Tfuobatillusferroaxidans, Thiobadllus thiooxidans, and
                                       i^.^i,..^?!1^16' me bacteria are placed hi a vat with sulfide gold ore.
                            ga ...... the:iiisulfide ...... rmnerals ..... and ..... fenpjis ..... iron components of the gold ore^  Research is
                          conducted on'other bacteria that can grow at higher temperatures; high-temperature
               y-r-.are .thought to trcat me ore ^ a ma<^ fester 5ffe OBureau of Mines, 1990^.  Although more
     :	"•	11;: time,is reqi!red_	for	bio-oxidatign,	it	is	considered,	ig.bejejs,expensive than roasting or autoclaving
;,«^^^^                         ..... ma
                                                                                   ^^^^^

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 ESA Guidelines for Mining                               Overview of Mining -and Beneficiation


 Heap Leaching

 Since the late 1970s,- heap leaching has developed into an cost-effective way to beneficiate a variety of
 low-grade, oxidized gold ores.  Compared to conventional cyanidation (i.e., tank agitation leaching),
 heap leaching has several advantages, including simplicity of design, lower capital and operating
 costs, and shorter startup times.  Depending on the local topography, a heap or a valley fill method  *
 may be employed.  Where level ground exists, a heap is constructed;.the heap consists simply of a
 flat-topped pile of the ore to be leached. In rough terrain, a valley may be dammed and filled with
 the ore.  Sizes of. heaps and valley fills can range from a few acres up to several hundred.  The
 design of these leaching facilities and then- method of operation are quite site-specific and may vary
 over time at the  same site. Gold recovery rates for heap and valley fill leaching generally range from
60 to 80 percent, but may be higher in some cases.


Leaching.  Heap leaching activities may involve any or all of the following steps (Bureau of Mines,
 1978 and 1984; van Zyl, 1988; many others):


      •   Preparation of a "pad" (or base under the heap) with an impervious liner on a 1 ° to 6°
         slope or greater for drainage. No gold heap or valley fill leaches are known to operate
         without a liner (Hackel,  1990).  Some liners may simply be compacted soils and clays,
         while others may be of more sophisticated design, incorporating clay liners, french  drains,
      •  and multiple synthetic liners.

      •   Placement of historic tailings or other relatively uniform and pervious material on the liner
         to protect it from damage by heavy equipment or other circumstances;

      •   Mining ore (or, as has been practiced in Cripple Creek, Colorado, and elsewhere, taking
         material containing .gold values from old waste piles or coarse tailings).

     •   Crushing and/or agglomerating the ore (agglomeration is discussed below), typically to
         between 1/2 and 1 inch in size if necessary and cost-effective; some operations may leach
         run-of-mine ore.

     •   Placing the ore on the pad(s) using trucks, bulldozers, conveyors, or other equipment.

     •   Applying cyanide solution using drip, spray, or pond irrigation systems, with application
         rates generally between 0.5 and 1.0 pounds of sodium cyanide per ton of solution.  This is
         known as the "barren" solution because it contains little or no gold.

     •   Collecting the solution intercepted by the impervious liner via piping laid on the liner,
         ditches on the perimeter of the heap, or pipes/wells through the heap into sumps at the liner
         surface. The recovered solution, now "pregnant" with gold (and silver), may be stored hi
         "pregnant" ponds or routed directly to tanks for gold recovery, or it may be re-applied to
         the heap for additional leaching.
         Recovering the gold from the pregnant solution.
                                            3-45                              September 1994

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             Overview of Mining and Benefication
                                                                         EIA Guidelines for Mining
                I
             Two common types of pads are used hi gold
             heap leaching:  permanent heap construction on
             a pad where ore is placed, leached, and left in
             place; and aictoiFiiacisi	——	—	^	^g^ Qn

	'	flic pad,	fc^lsi,	,SJ,	,22121	£,	m Vcn$?:?snt
	  disposal site, after which more ore is placed on
,1 ^ j	tmw^m  the pad for a new cycle.  Permanent heaps are
                     built in successive lifts, with
                                                                            	,	I	i
                                                    ' Agglomeration. Ores with a high proportion of
                                                   :;•' small particle size (mhms 200 mesh) require
                                                     additional preparation before leaching can be done
                                                     effectively.  Because percolation of the Uxiviant
                                                     through the heap may be retarded as a: result of
                                                    preventing the solution from contacting and
                                                    recovering the gold from sections of the heap),
     11	lil""""	v
 composed of a 5- to 30-foot layer of ore.  Each
 lift is men leached, a new lift is added to the •
     IP             i
 top and leached, and so on, until the heap
 reaches its final height, which can range up to
 200 feet or more,, On-off pads are much less
 common in the industry (Lopes and Johnston,
 1988).'            •
                    : /increase particle size.. Agglomeration aggregates
                      individual particles iito a larger mass, thus
                   . • ;• enhancing percolation of the lixiviant and -
                   ffs extraction efficiency: This technique may  '    <
                   ; ^increase the flow of cyanide solution through the
                     :heapby:a^factor:of 6,000, decreasing the overall
                    •  leaching time needed.: Agglomeration is currently
                   ,.  used in about half of all heap leaching operations,
                   :  -The agglomeration technique typically involves   "
                    " the following (Bureau of Mines, 1986).%
            marerfals vary withme'iype of pad, site
            conditions, and perhaps most importantly,
            regulatory requirements.  Construction materials
         •llllll I I 111 111 111 llllllllilH   llllll lllllllllini I  IIII	,	;	
            may include compacted soil, or clay, asphaltic
            concrete, and low-permeability synthetic
	membranes such as plastic or geomembrane
lllliillllll     	Illlilllllllllllllllli 11 lliill  lllllijllliillllll            	I	i	n    	     i
	„	(van Zyl et al., 1988). As noted above, sand,
•M          I  llllll l|ll III 11 in in n in i iiiiiiiini i iiiini iiinnilliwili i in iiiinnni inn iininininn inn niinnnn inn inn 11 n  inn muni mi ninnm  i
           historic tailings, or crushed  ore may be placed
	•	  on top of the synthetic liner to provide a  •
           pervious medium for leachate collection as well
           as to protect the pad.  Older pads tend to be
                                  ', with little or no other
made of compacted

site SSSSSSh ............... JJfZ? P3^ are
                                                 ' *. " -

                                                 fltlf  ^i
                        •• Adding Portland cement (a binding agent)
                          and/or Bme (for alkalinity) to the crushed ore
                          as or before It is placed on the heap

                          Wetting the ore with cyanide solution to start :,;
                          leachhig as or before the ore is placed on the ..,;::
                          heap (e.g., spraying cyanide solution over
                          ore on the conveyor that transports ore from •
                          the crusher to the heap)          ^.'
                                                      • Mechanically tumbling die ore niLuure so
                                                        fine partides adhere to the larger particles.
                                                        This can occur, for example, when ore is
                                                        damped from the end of a conveyor or truck
                                                      :,. and then mechanically spread on the heap.
           IS5E ...... ojPna^ye soil or imported clay.
                                                                                   » ...... .typically installed over a
                                                          Some mines now use synthetic liners composed of
                                               are
                                                                          ...... 001^05^ liners; dependmg
                                           s, there may be a leachate collection system between the liners to
           detec^ and coUect any leakage through the primary liner.  On-off pads are generally constructed of
           asphaltic concrete to protect the liner from  potential damage by heavy machinery used during
           unloading.
Illllllllllllli    	llllll	 llllll 1(1,111
               ill
n	i iiiiii nil
i	i
iiiiiiiiiiini in i "i	in	nil
I  iii1 it i	ill
                                                         3-46
                                                                                  September 1994

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 EIA Guidelines for Mining                                Overview of Mining and Beneficiation

 As notecj above, a variation of heap leaching is valley fill leaching.  This method is used at facilities
 with, little or no flat land and. utilizes liner systems similar to those used hi heap leaches for solution
 containment.  In valley fill leaching, the ore material is placed on top of a liner system located behind
 a dam on the valley floor.  As in heap leaching, the ore is treated with lixiviant but is contained and
 collected internally at the lowest point hi the ore on the liner system for further beneficiation, rather
 than hi an external solution collection pond. Montana, Utah, and other States have approved valley
 fill operations.

 In either of these two configurations, cyanide complexes with gold and other metals as the barren
 solution percolates through the ore. Leaching typically takes from weeks to several months,
 depending on the permeability and size of the pile. An "average/normal" leach cycle takes
 approximately three months (Lopes and Johnston, 1988).

 The reaction of the solution with the free gold is oxygen-dependent.  Therefore, the solution is
 oxygenated prior to application or during spraying.  Barren solution may be kept hi a barren pond
 prior to application, or may be routed directly to the heap from tanks.  Barren solution is made up by
 adding fresh water, cyanide, and lime to recycled water from the carbon columns (see below).
                       ,                                   *              „•
 After being applied to the surface of the ore by sprays or drip irrigation, the cyanide solution
percolates through the ore and is collected by pipes placed on the liner beneath the pile, drams
directly to ditches or ponds around the pile, or is recovered from sumps constructed at the liner
surface  (Bureau of Mines, 1986; Lopes and Johnston, 1988).  The solution is then collected hi a pond
or tank.  The pregnant solution pond may be used as a holding pond, a surge pond, or a settling basin
to remove solids contained hi the cyanide solution. Some operations use a series of ponds, which
may include one for the barren solution, an intermediate solution pond (from which semi-pregnant
solution is directed back to the heap for further leaching before gold is recovered), a pregnant
solution pond, and one or more emergency overflow ponds.                 .

These ponds may be single-lined but are now more often double-lined with plastic (HDPE),
butylrubber, and/or bentonite clay to prevent seepage.  Composite liners, often with leachate
collection systems to detect leaks are becoming increasingly common hi response to more stringent
States requirements.  Particularly hi the arid west, but also hi the east (e.g., South Carolina) wildlife
and waterfowl may be attracted to the ponds, and the cyanide solutions present an acute hazard. To
control wildlife access to cyanide solution, at least one operation (Castle Mountain hi California) has
elected to construct tanks to collect and store leachate solutions as an alternative to open ponds.
Many active operations now fence or cover solution ponds with screening or netting to prevent
wildlife or waterfowl access, respectively.
                                             3_47                              September 1994

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            pyerriew of Mining and Benefication           	       EIA Guidelines for Mining
               I      	'	                 I   	:	•	~	: •	'•	'	""""	"	"
            Leaching occurs according to the foUowing-reactions, with most of the gold dissolving in the second
            reaction (van Zyl et aL, 1988):
                 *   4Au + SNaCN + Qz + 2H20 -» 4NaAu(CN)2 + 4NaOH (Elsener's Equation and
    •  '       •  :      Adamson's 1st Eolation)
           1™=S ..... IsSsiP®* ...... ± ....... ft + 2H20 - 2NaAu(CN)2 + H2O2 + 2NaOH (Adamson's 2nd
iiiiiH         aiiilii               "
                                llri	111 Nil I lllllli III Hi 111111'	Ill	I	 lilill	liiliill	II  il  	  I illiili In Ilillll	 lililliill il	I	lull	Ill	II   111
          	,	i	      	,	-	:	*	being approximately 10.5.
                	SSlS	ffiSSiSS	ffiay result in the loss of .cyanide through hydrolysis, reaction with carbon
Bj^K	spill	2£	Sc^S§,,,liydrogen to form hydrogen	cyanide	(HCN).	Alternatively, more basic '
    ",      coidpons tend to slow the reaction process (Bureau of Mines, 1984)  Typically, the recovered
           cyanide solution contains between 1 and 3 ppm of gold material (Bureau of Mines,  1986).  Leaching
           continues until me gold concentration in pregnant solution fells below about 0.005 ounces per ton of
	S^EE^SS	25	Ife!0!^	!?„§§>!	SlS	&*	OMUK	at permanent heaps, another lift is added and
	"	|	"leached or	tfaehejip is prepared for closure.    '         	:	:	
          Barren solution must be treated to reduce cyanide levels to regulatory levels— cyanide species
          regulated can be weak-add^isso^  ....... gee, ....... or total ...... cyanide-when recycling is no longer necessary.
          Treatment occurs when contaminants ....... build ..... up ..... in ..... the ...... recycung^c^dej.solution, at the .end, of leaching.
          seasons, and/or at facility closure. Defending on regulatory '~Teqtirmaa, the wAitian^r'aeii be
          land applied, stored in ponds, or evaporated.
                              "    .................................... : ..................... [ [[[ v": ...... : ........................... ;||; [[[ l ......... ' ............ \  ................  '
          Whenleaching ends, me spent ore that makes up the heap usually remains in place.  Whereon-off
                       however, spent ore will have been successively removed from the pad for disposal in
                                 ***            «      fi^SE » 5» .SHiM .tpm, g&off. pads),  the
                                                        — .....   __ ...... - ...... ,_  ......
                                            I. This is..    _      ^	^ _r	o	
          wat^TIstlally ^ WJtter OT aSSL «***»*«•  Hydrogen peroxide or other oxidants may be added to
          J*^6 f31618- Cyanide in rinse water may be treated using one or more of the methods described
              5iL,i,»M,2	222	SEE	ISS^???,	E,,???!*1^	,*la™^,,,,c51ceittrations,	m	rinse	water/leachate to •
                                                     •fe heap can be reclaimed and/or abandoned. The
                                      ;	i	ejMnnousl|;	variable,,	ranging from a few days for some on-off
                                 .....     ......
i ...... i ........ i» ................ •» .......... » ............ ............. heaps to months or  ears for some
                                                                            .
                                                                                                 i1 Hill Ilii ili iiillll liiliill1 111 ill i  "
                         Se*pd.fflrt completeness of detoxification, spent ore may continue to have a high
         pH. Heaps with agglomerated ores may prove particularly difficult to detoxify, since this tends to
         keep pH high. Reclaimed piles may have passive controls to control run-on and runoff; the design

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 EIA Guidelines for Mining                               Overview of Mining and Benefidation
 or the probable iroxmmTn precipitation event, depending on the component and State regulatory
 requirements.
                                                3.

 If sulfide ores are present, they may generate acidic leachate over time, which in turn may mobilize
 heavy metals that are present in the ore.  Although heap leach piles are generally lined, liners may be
 damaged or may deteriorate, or may be intentionally punctured as part of reclamation.


 Current technology and environmental concerns have led to the development of several methods for
 complexing or decomposing cyanide. These include:

      •  Lagooning or natural degradation through photodecpmposition, acidification by CO2 and
         subsequent volatilization, oxidation by oxygen, dilution, adsorption on solids, biological
         action, precipitation with metals, and leakage into underlying porous sediments.

      •  Oxidation by various oxidants:

             Chlorine gas
             Sodium and calcium hypochlorites
         -   Electro-oxidation and electrochlorination
         -'  Ozone                 ^
         -   Hydrogen peroxide                                                         :•
      .   -   . Sulfur dioxide and air.

         In all cases, cyanide  is oxidized initially to the cyanate, CNO .  In some cases the cyanate
         ion is oxidized further to NH<+ and HCO3-, and finally the ammonium ion may be
         oxidized to nitrogen gas.                          •

      •   .Acidification, with volatilisation and possibly subsequent adsorption of HCN for reuse.

 ;     •   Adsorption of cyanide complexes on ion exchange resins or activated carbon.

      •   Ion and precipitation flotation through cyanide complexation with base metals and recovery
         with special collectors.

      •   Conversion of cyanide to less toxic thiocyanate (CNS") or ferrocyanide (FeCCN)^4".

      •   Removal of ferrocyanide by oxidation or precipitation with heavy metals.

      •   Biological oxidation.

Hydrogen peroxide, for example, can be used to detoxify cyanide in spent heaps, tailings, and
solution ponds and tanks.  The cyanide-bearing solution is sent to a series of hydrogen peroxide  .
reaction tanks (Ahsan et al., 1989). Hydrogen peroxide and lime are added to the solution forming
precipitate of metal hydroxides and oxidizing free and weakly complexed cyanide into cyanate
(OCN-).  Additional steps precipitate copper ferrocyanide, a reddish-brown solid that is stable at a pH
                                             3.49                              September 1994

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               i:	:	1!	-:	;	;	;	,:	!	;	:	;	j	;	:	:	:	:	±	_:	;,:	;
                                                                                       !
                                                                             ' " ''   '   1  '              '   ' •
            Overview of Mining arid Beneficiation	;	OTA. Guidelines for Mining

            of less than 9. Precipitates are separated from the solution and discharged to the tailings
            impoundment. The solution is then recycled until the desired cyam'de concentration is attained in the
       	  effluent.      ,                         '

            INCO has also developed a technique for detoxification of mine waste streams containing cyanide—
            such as CIP and QL pulps, barren solution, tailings pond waters, and heap leach rinse solutions—by
            removing cyanide and base metal complexes.  The INCO process uses SO2 and air; which is
            dispersed in the effluent using a well-agitated vessel. Acid produced in the oxidation reaction is
            neutralized with lime at a controlled pH of between 8 and 10.  The reaction requires soluble  copper,
            which can be provided in the form of copper sulfate (Devuyst et al., 1990).
                     	" 	V  '    ' , 	i    (i if mi	if in in111!	i in I Hi"!"! 11 "i	i ill I	miii  11 11 ill	i	nil"!1 nidi in
           Each treatment method may generate a different waste, with the chemical compounds used in cyanide
           removal as constituents.  Someof these (e.g., chlorine, ozone, hydrogen peroxide) are toxic to
           bacteria and other life forms but' are unlikely to persist or can be cleaned' up easily. Others (e.g.,
           chloramine or chlorinated organic compounds) may persist for long periods in the natural
           environment.  In general, the long-term persistence of cyanide residues in mining waste are not
           completely understood (University of California at Berkeley, 1988).
        I III  I III  ill III I III III III
           Following detoxification, heaps may be regraded to more stable long-term configurations. Liners
           may be punctured and the heap covered with topsoil and reclaimed/revegetated. In some cases, heaps
	may require capping to reduce leaching of heavy metals. Reclamation requirements vary among the
           States, and the types of reclamation that are suitable for a given heap generally depend on the nature
           of the site and of "the spent.ore. Any:ponds are usually backfilled. Pond'"linere 'rnayjtejemoved,
           folded over and sealed to encapsulate sludges or other wastes, punctured, or otherwise handled,
	i	depending on State	requirements.  Because of the enormous amounts of spent ore hi heaps/valleys and
     •in spent ore dumps, any long-term environmental problems must be anticipated during design, since it
           is not practical to	move tijejnaterials	after'. (operations	"""~	"	
     , 1 1 III 111 I "I ill Illllllllll III! Illllllllllllll Illllll           ,        ..... llllllllliil ....... }
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   EIA Guidelines for Mining	Overview of Mining and Benefication

   Activated carbon techniques are better able to process solutions with low metal concentrations and are
   thus most often used on solutions with a gold concentration below 0.05 oz/t of solution (Bureau of
   Mines, 1978 and 1984). Carbon adsorption is used both for heap leach solution and for tank
   leaching.

  In heap leaching, carbon adsorption uses the Carbon-in-Column (CIQ technique.  In the CIC
  technique, the pregnant solution collected from the leach pile is pumped from a collection pond or
  tank into a series'of cascading columns containing activated carbon. The solution mixes with the
  carbon column in one of two methods:  fixed-bed or fluid-bed.

  The fluid-bed method involves pumping pregnant solution upward through the column at a rate
  sufficient to maintain the carbon bed in a fluid state moving gradually down through the column
  without allowing the carbon to be carried out of the system. Thus, loaded carbon can be removed
  from the bottom of the tank and fresh carbon added at the top.  The fluid-bed method is the more
  common of the two methods used in operations adsorbing gold-cyanide values from unclarified leach
  solutions containing minor amounts of slimes.  Because the fluid-bed method uses  a countercurrent
  operating principal, it is often more efficient and economical than the fixed-bed method in adsorbing
 the gold-cyanide complex from solution (Bureau of Mines, 1978 and 1984).

 In the fixed-bed method, the gold-laden cyanide solution is pumped downward through a series of
 columns. The columns generally have either flat or dished heads and contain a charcoal retention
 screen as well as a support grid on the bottom.  Normally, the height-to-diameter ratio of the tanks is
 2:1, although, in some instances, a larger ratio will increase the adsorption capacity of the system
 (Weiss, 1985). In each vessel, the gold-cyanide complex is adsorbed onto activated carbon granules
 that preferentially adsorb the gold-cyanide complex from the remaining solution as  the material flows
 from one column to the next. The advantage of the fixed-bed method over the fluid-bed method is
 that it requires less carbon to process the same amount of solution (Bureau of Mines, 1978 and 1984).
                                                                                            *
 Elution.  Typically, the activated carbon collects gold from the cyanide leachate until it contains
 between 100 and 400 ounces of gold per ton of carbon depending on the individual  operation.
 Loading efficiency decreases with solutions containing less gold (Bureau of Mines,  1978). The
 precious metals are then stripped from  the carbon by elution.  The values can be desorbed from the
 carbon using a boiling caustic cyanide stripping solution (1.0 percent NaOH and 0.1 percent NaCN).
 Modifications of this method include the addition of alcohol to the stripping solution and/or stripping
under elevated pressure or temperature (40°C to 150°Q (Bureau of Mines, 1986).  At least one
mine, Barneys Canyon, uses a stripping solution of hot sodium hydroxide that has proven to be as
effective as caustic cyanide (LeHoux and Holden,  1990).
                                            3-51                             .September 1594

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                                 IIIIIIIIIIIIIIIII llllllllllllllllllllllll 1 III II Illllll 1111 Illllll 111 Pl|l|lllllll|llll I IIIIIIIIIIIIIIIII 111 111 111 111 Illllll III IIIIIIIIIIIIIIIII 111 l|lllllll Illllll Illllll IIIIIIIIIIIIIIIII Illllllllllllllllllllll Illllll lll|l IIIIIIII III Illlllllllllllllllllllllllllllllll •••llllllllll IIIIIIII I Illllll IllllllllIIIBIH   I IIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIII
  iiiiiiini i1 iiiiiiii
              Overview of Mining and Benefication	         EIA Guidelines for Mining
                i                         i                                         *    i     i
                                     •                                                      i
              Carbon uses! in adsoiption/desorption can be reactivated numerous times.  The regeneration technique
            	varies	with	rnj^ng'operations,	but generally involves an acid wash before or after elution of the gold-
              cyanide complex, followed by reactivation in a kiln and re-introduction into the adsorption circuit
              (Bureau of Mines, 1985).  Generally, activated carbon is washed with a dilute acid solution (pH of 1
              or 2) to dissolve carbonate impurities and metal-cyanide complexes that adhere to the carbon along
                I,                  '                     '       .  .      " • i      '   ,., ,      ,  i' '               "
             witjh the gold.  This technique may be employed either immediately before or after the gold-cyanide
             complex is removed.  Acid washing before the gold is removed enhances gold recovery.  Based on
                I  '    I,       '     i ,»in* i  •  ',"•:  "•'     '          ,"•   ' , •'„ '-' '   ' ' ,  •'; •  ,  ! " ' ''i , „" ,	i;	'	FT:	s"";"" * "   • •
             impurities to be removed, from the carbon and metallurgical considerations, different  acids and
             concentrations of those acids may be used. Usually, a hydrochloric acid solution is circulated through
             3.6 metric tons (4 short tons) of carbon for approximately 16 to 20 hours. Nitric acid is also used in
             these types of operations, but is thought to be less efficient than hydrochloric acid (HCL) in removing
             impurities.  The resulting spent acid wash solutions may be neutralized with a high-pH tailings slurry,
             dilute sodium hydroxide (NaOH) solution, or water rinse. When the wash solution reaches a stable
             pH of 10, it is typically sent to a tailings impoundment. Metallic elements may also be precipitated
             with sodium sulfide (Smolik et al., 1984; Zaburunov, 1989).
              .  11   	ii	i	in	pij^^^	I1*"	i	i	i	•      i     i MI   i      i         i      i        'i
                                        •                                         i         i
             The carbon is men screened to remove fines and thermally reactivated in a rotary kiln at about 730°C
           . for 20 minutes (Smolik et al., 1984).  The reactivated carbon is subsequently rescreened and
            xenttrodoced into the recfiyejy system. Recirculating the carbon material gradually'decreases
            performance in subsequent adsorption and reactivation series. Carbon adsorption efficiency is closely
            monitored	and fresh i carbon is	added	^maintain efficiency at design levels (Bureau of Mines, 1984
  "          and 1986)1	:	
iiiiiiiiiiiiiiiii iiiiiiiiiiiii           _          iiiiiiiiiiiiiiiii	i-	   .              "                      *
                            f01 °f optnnum size are either lost to the tailings shiny or, to the greatest extent
                                '"""""SS?^00*  C?rbon lost to me circuit fc rep130641 with virgin, optimum-
                                from	I!?	,rjeactiyatipn,,,,,cjrcu|!s	.may include carbon fines and the acid wash
            solution. The carbon may contain small amounts of residual base metals and cyanide.  The acid wash
            residues may contain metals, cyanide,  and the acid (typically hydrochloric or nitric); according to
            Newmont Gold Company, the acid is usually neutralized in a totally enclosed system prior to release.
            Up to 10 percent of the carbon may be lost in any given carbon recovery/reactivation circuit from
            abrasion, ashing, or incidental losses.  Most operations capture less-than-optimum-size carbon
    *      particles and extract additional gold values (or send fines offsite for gold recovery).  Onsite or offsite,
           this may involve either incinerating the carbon/gold that could not  be desorbed chemically durine the
                 .                                        	'	—-—	JJ2J	WJJ	•»»»•»»»* J»w»»	MMUUMUIJ	UlUUlg Ulb
                  	gSSSSSMii.SP^ti0118 or subjecting the material to an extended period of concentrated cyanide
                   T	—	r1-*1	-	-	-	:	-	:	'   	  -          J
                   SIS	Squids	255?,!?	*****OT transport carbon material are recirculated.
        ;;^SflJdLBssai3!!SD[.  Gold hi the pregnant eluate solution may be electrowon or zinc precipitated.
                                               1 uses stainless or mild steel wool, or copper, as a cathode to
!!=^^^^^              	US	goW product. After two or more cycles of electrodeposition, the steel wool must be
    SIlnfH     /'iill^                lllllir'''!IWWH«WB!llfll 'ii'i' 1	' "I'l   ' iiiiiiii liiiiiiiii'i'iii' Jiii! lfi" lftiMBIi 'iii'iii'i BKDOHJIWiliTl iii'iiiiliiiiiiiii'ii'iiiiii  i  iiiii	""ii "ii iiiiiiiiiiiiiiiii mmi"   i	iiiiiiii

                              iii/'iiii ii W n ^	i	i	'.I'"	•"	i1"!1	r	i	• 3-52              . '              '   September 1994
            !•; n 'iiiiiita    	iiii'ii ill1'iiiiiBiiiiB            	iiiiiiiiiiiiiiini 1 ii, i i"i	11  i iii'iiiiiiii" i iiiiiniiii in n i ii	IK iiiiiiiii iiiii( I'll  ill, "ill iiiiiii'iiiiliiiiiiiiiiiiiiii'iiii'ii i iBiiiiiiiiriiii'i i	r iiiiiiiiiiiiiiii'iiiiiiiii i 111 ifiii	i	iiiiiiiiii	iiiii  i  iiiiiii "i in in ny ii 11	  i	iiiii

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   EIA Guidelines for Mining                               Overview of Mining and Benefication

   removed and replaced. The depleted stripping solution may then be reheated and recycled to the
   carbon stripping system.  The steel wool or electrowhming sludge, laden with gold value, is fluxed
   with sodium nitrate, fluorspar, silica, and/or sodium carbonate and melted in a crucible furnace for
  casting into bullion. For gold ores containing mercury, a retort step is required before gold smelting
  to recover metallic mercury (Bureau of Mines, 1986; Smolik et al., 1984).

  Although carbon adsorption is the most common method of gold recovery in the United States, zinc
  precipitation is the most widely used method for gold ore containing large amounts of silver. Because
  of its simple and efficient operation, die Merrill-Crowe process is used at the  10 largest gold
  producing mines in the world, all of which are in South Africa.  This technique is well suited to new
  mines where the ore has a high silver to gold ratio (from 5:1 to 20:1) (van Zyl et al., 1988).

  In zinc precipitation operations (the Merrill-Crowe process), pregnant solution (or the pregnant eluate
  stripped from the activated carbon) is filtered using clarifying filters coated with diatomaceous earth
  to aid in the removal of suspended particles (see Figure 8) (Weiss,  1985). Dissolved oxygen is then
  removed from the solution using vacuum tanks and pumps. This is necessary because the presence of
 oxygen in the solution inhibits recovery (Bureau of Mines, 1984).

 Metallic zinc dust then  is combined with the deoxygenated pregnant solution. At some operations, a
 small amount of cyanide solution and lead nitrate or lead acetate is added. Lead increases galvanic
 activity and makes the reaction proceed at a faster rate. Zinc precipitation proceeds according to the
 reaction described below; the result is a gold precipitate (Bureau of Mines, 1984).

             NaAu(CN)z + 2NaCN +Zn +H2O  -  NajZ^CN^ + Au  + H  + NaOH.
 The solution is forced through a filter that removes the gold metal product along with any other
 precipitates.  Several types of filters may be used, including submerged bag, radial vacuum leaf, or
 plate-and-frame.  The gold precipitate recovered by filtration is often of sufficiently high quality (45
 to 85 percent gold) that it can be dried and smelted in a furnace to make dor6 (unrefined metals). In
 cases where further treatment is necessary, the precipitate may be muffle roasted or acid treated and
 calcined with borax and silica before smelting (Weiss, 1985). Following filtration, the barren
 solution can be chemically treated (neutralized) or regenerated and returned to the leach circuit
 (Weiss, 1985).

The wastes from zinc precipitation include a filter cake generated from initial filtering of the pregnant
solution prior to the addition of zinc, and spent leaching solution, which is often returned to the
leaching process.  The filter cake consists primarily of fine gangue material and may contain gold-
cyanide complex,  zinc, free cyanide, and lime. The filter may be washed with water, which is
disposed of as part of the waste.  The waste is typically sent to tailings impoundments or piles.
                                            3-53                              Seotember 1994

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                            	II	
                                                                     r'^inSiSivililliilpiiu        	"lifii,1!!? SBS
      U11Ifllli!'1 quit >gil,i!l l!^lh,i' 11lllllffi^             	•Illllli I 'ill1 Itll	" i J'I'IW
                                                                                      iiiiii:"ii'u!j|iiiiiiiiii iniiiiiiiii ..... IIIIMIIIIII
                                 and               •                     •       •       '
            Tank Leaching
                                                                                       	i	
            As nojeji previously, tank leaching techniques ifoFgdd recove^" ''are pre^red over heq> iieaching"f6r
            higher-grade ores, typically those with gold values averaging over 0.04 troy ounces per ton of ore.
            In tank leaching operations, primary leaching takes place hi a series of tanks, often in the mill
            building, rather than in heaps. Finely ground gold ore is slurried with the leaching solution hi tanks.
            The resulting gold-cyanide complex is then adsorbed on activated carbon.  In the Carbon-in-Pulp
               I  • •  .  •" '   ;     t,j    i-     •    -  ;!"     i         •    ..... r '• '• .....   • ,      •'.!:.     '   ,  >•    '
            method, leaching and adsorption 'occur in two separate series of tanks; in the Carbon-in-Leaching
           ..... method, they occur- in a single series.  Both are described below.  In either,  the pregnant carbon then
           : undergoes elution, followed either by electrowuming or zinc precipitation, "as described previously.
            The recovery efficiencies attained by tank leaching are significantly higher than'for heap leaching.
                          typically recover from 92 to 98 percent of the gold contaned hi the ore.
                                                                                          1
            Continuous countercurrent decantatibn (CCD) is a method of washing the solution containing metal
            values from the leached ore slurry to produce a clear pregnant solution.  This procedure is used for
            ores with high silver values that preclude the use of activated carbon and that are very difficult to
           filter,	thus	precluding	the use	of filters.	The resulting pregnant solution is generally treated by the
           zinc precipitation technique described above.      ,                  •            .

           A new technology employed in South Africa uses ion exchange resin in place of carbon in the CD*
                     " ............... This ...... gg^j(^y_^^jn^^   ...... ^^p^,,,,__^ ...... _.. ..... _^_ ..... __^ ..... ££jj ..... ^o^'and ...... energy

          i-'te use o ion exchange resins is found to be gQ^z^ggg ...... — — — ...... -— - ..... — -- ...... .-.-—- ..... .__ ......
          IliliiW^^^^^^^^                   ......                         .......................................... ' [[[ -,,~ ............................. ; [[[ •, ..... - .................. , ........... ' ...... ' ....................... : ........................ !!, ............... ' ..... ,
              ftto "
                                                                                   inn" i|"iii	!i|vi ininiipi qiiiii .|..uiiiiii:.ii|iii|niii	m'l'i	f. > inraini'in'iiiiiiiiiiiiiiiiiiiii	"»'., iJ:"
           Caifeonrte-ulpjClP).  In the OP technique, a Slurry of ore, px'vt''cyaiae, and' lime" fe
                                                        |
 ;          punned jjjj^jgjj a series of tanks for agitation and leaching. Then, the slurry containing leached ore
           and pregnant solution is pumped through a second series of tanks for adsorption (or subjected to
           continuous countercurrent decantation).
  •ill I 111(111 111 Illi  IK  lllllllliillllli ilillililllli	lillllllllll	lllllllllllllllllllliil	ill I
                                           	I	 »
           In the second series of CDP tanks, the slurry is introduced into a countercurrent flow with activated
i                i                                                                          i
           carbon. The slurry enters the first tank hi the series, which contains carbon that is partially loaded
           with the gold-cyanide complex. In the suspended slurry, the activated carbon adsorbs gold material
           on the available exchange sites. As the carbon material becomes laden with precious metals, the
           carbon is pumped forward in the circuit toward the incoming solids and pregnant solution.  Thus, in
           the last  tank, the low-gold percentage solution is exposed to newly activated and relatively gold-free
           carbon that is capable of removing almost all of the remaining precious metals in the solution.  Fully
           loaded carbon is removed at  the feed end of the tank tram for elution, followed by electrowinnhig or
ES«ii£!s^!fi precipitation 'as described previously. (Bureau of Mines, 1978 and 1986;  Stanford, 1987)..

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 EIA Guidelines for Mining                                Overview of Mining and Beneficiation

 Carbon-in-Leach (CIL). The CIL technique differs from CIP in that activated carbon is mixed with
 the ore pulp in a single series of agitated-leach tanks. Leaching and adsorption of values occur hi the
 same series of tanks.  A countercurrent flow is maintained between the ore and the leaching solution
 and activated carbon.  In the first tanks of the series, leaching of the fresh pulp is the primary
 activity.  In later tanks, adsorption is dominant as fresh carbon is added to the system countercurrent
 to the pulp. Adsorption takes place as the gold-cyanide complex mixes with the carbon. As with
 Carbon-in-Pulp and heap leach operations; the pregnant carbon undergoes elution to remove values.
 The pregnant elttate then undergoes electrowinning or zinc precipitation to recover the gold.

 The number and size of tanks used in domestic CIP and CIL facilities vary.  For example, the
 Ridgeway facility in South Carolina uses 10 tanks measuring 52 feet in diameter and 56 feet in
 height; the  Mercury Mine uses 14 tanks, each of which are 30 feet  in diameter and 32 feet in height;
 the Golden Sunlight Mine uses 10 tanks, each of which are 40 feet  in diameter and 45 feet hi height.
 Retention times vary as well, ranging from 18 to 48 hours, depending on the facility, equipment used,
 and ore characteristics (Smolik et al., 1984;  Fast, 1988; Zaburunov, 1989).

 For either CIP or CIL, ore preparation (including grinding, lixiviant strength, and pulp density
 adjustment) and the time required to leach precious metal values vary depending on the type of ore.
 Oxide ores  are typically beneficiated by grinding to 65 mesh and leaching with 0.05 percent sodium
 cyanide (for a pulp density of 50 percent solids) over a 4- to 24-hour period. Sulfide ores are
 typically beneficiated by grinding to 325 mesh and leaching with 0.1 percent sodium cyanide for a 10-.
 to 72-hour period (for a pulp density of 40 percent solids) (Weiss, 1985).

 Both of these tank beneficiation methods produce a waste slurry of spent ore pulp, or tailings, which
 is pumped as a slurry to a tailings impoundment (Bureau of Mines,  1986; Calgon Carbon
 Corporation, undated; Stanford,  1987).  The tailings slurry is composed primarily of spent ore and
 water, along with small (but sometimes significant) amounts of residual cyanide, lost gold-cyanide
 complex,  gold hi solution, and any constituents  hi the water, including those added to control scale.
 The solid component of tailings consists of very fine materials, ranging from sand-sized to talc-sized.
 The characteristics of tailings vary greatly, depending on the ore, cyanide concentration, and the
 source of the water (fresh or recycled).  In some .cases, the tailings slurry may be treated to neutralize
 cyanide prior to disposal.

Tailings are disposed of hi large tailings impoundment (up to hundreds of acres).  Disposal requires a
permanent site with adequate capacity for the life of the mine.  The  method of tailings disposal is
 largely controlled by the water content of the tailings.  Generally, three types of tailings may be
 identified  based on then- water content: wet (greater than 40 percent of the total weight is water),
thickened  (approximately 40 percent water), and dry (less than 30 percent water).  Where topography
allows, tailings impoundments are located near the mill, but pipelines can be used transport tailings to
                                             3-55                              September 1994

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                                            tf "i
                                            b
              pgg	i|;;Mjijgg and Benefication •     	'      	 EIA Guidelines for Mining-
         suitable locations a male or more away (always downhill).  The design of tailings dams depends
         prfiarily on the topography and the configuration of the impoundment (see Section 3.2.6); the
   "  "  preferred method is for the dam to span a valley, with tailings impounded in the vallev  Dam
           (ill ...... 1(1 ......... i ...... l ........................ _ ...... l .................................. l ..................... i ................ 1 .......... ill [[[ I [[[ ilil ....... Hi ..... ill ........ iiiii ..... iiiiii ..... ill ................................... , ....... 1 [[[ 1 ........... 8 ................. .............. iiSm .................... i [[[ , .................................. ........................................ J ' .......... __1!J, [[[
         construction materials include native soils and clays, waste rock, and components of the tailings (e.g.,
         coffser ss^s ^ pff^111.31638 of ** dam and frra "slimes" on the upper face.  Dams must be
         engineered to withstand seismic events, and to control the flow of liquids through or under the dam to
         prevent catastrophic Mure. Dam design must also consider water flow in the drainage following the
         act*ve ***   °f tte mine, since free water is ticall  ket to a minimum
                        mine, since free water is typically kept to a minimum during operation by recycling
         it b(ack to" the roll. '
           I                                                  HI           H   |
           '                          «                                 "
         In rjart because of the Clean Water Act requirement that there be no discharge from gold beneficiation
                      use_cyanid^ttira methods,- most of the liquid component of tailings is recycled back to
               . Newer tailings impoundments are on prepared surfaces of compacted soils and clays, with a
            unpoimdments using clay or synthetic liners. In addition to water in the tailings slurry, .there can
              j^^ -| ^j^^ r^ ^ impoundment (this volume of water may be. discharged under
                 ..... Sis ..... iffk ..... ..... & ..... 2S2,5,,,2S ...... ss, ..... & ..... te ..... SsSioasSiSary to *»i&s* ..... sns ...... °i ...... m°i« ....... seepage
             SSSSISS ....... SSSSfity ;downgradient of the tailings dam.  This has proven necessary for
    ^3jj%s»l interrelated reasons: the zero discharge effluent u^mjtatign'guideunes, which requite
                                    '         seepage to groundwater; State groundwater protection
                                                                          "
;=^               ....... ^,,,,;I?qgire lineis or other means to reduce^ the ]ps$ of fluids" to the, sjAsurfece; the
[[[ ?!!^* ...... ^"?§S?i ........ !5-^:.^Sg ....... §9™ P*L *!jy ....... S^L Haffi grouridwater infiltration;11 and the need to
        control the movement of fluids through or under the dam.  During the active life of the mme,
        solutions captured 'in such ponds are generally pumped back to the impoundment itself or directly to
        the mill.
                            1                                                     '
                                                                                 i
        States usually require reseeding/revegetation of impoundments when the mine closes.  Because
                    ...... are ..... often ..... to ...... diainaies, ....... redamation ..... may include ..... pennanent ...... .diversions, ..... .around, ..... the
Ill III 11111 111 111lllllll
  Hi I 111
                    ......   .....     .....  ......         .......           .....           .....         ...... ., ..... ., .....
       tailings or gating 3^^ over or through the tailings.  Reactive tailings (e.g., acid-forming) may
       fc^, ..... f0,,,,^ ..... Sffi! ..... ,!^!2S ...... SlSSXiPft ^ ro°t penetration or erosion of any such caps may have to  '
       be considered in reclamation planning,                            ,             .      *
                                               .
            I ,
       33J;    GOLD PLACER MINING

       Placer mines have historicaUy produced approximately 35 percent of the total U.S. gold production.
       iKgSfr, ..... SHE ...... SI £°}d pwduj^ntai ....... mcreased, ...... annually in recent years, placer production has
       decrt[ascd ^ *» readily accessible placer deposits have been mined put and with the development of
       S^j ...... SSSfeSffi ..... Kfifffi10^ ....... IbFmlning ....... and ..... bradBda^g ..... lode ...... deposit ............... placer ..... rnines produced

-------
 EIA Guidelines for Mining                                Overview of Mining and Beneficiation

 The size and nature of placer mines range from open cut operations disturbing tens of acres annually
 to small sluices operated solely as a recreational activity. In 1987, the average number of employees
 at placer mines in the contiguous 48 states was between three and four, and few mines employed
 more than 10 people (EPA, 1988b).

 Regardless of size, most placer mines operate on a seasonal basis (ADEC,  1986; EPA,  1988a).  The
 small size of .most placer operations and the relative ease in establishing an operation make it difficult
 to establish the number of mines operating at any one time (EPA, 1988a).  A 1986 EPA survey
 showed a total of 454 placer mines in operation in the U.S. Also in 1986, the Bureau of Mines
 estimated there were just more than 207 operational placer mines. While the final totals are quite
 different, both surveys revealed the overwhelming majority of the mines were in Alaska (190
 according to EPA and 195 according to the Bureau).  All the mines  identified in both surveys were
 west of the Mississippi, with most large operations in. Alaska.

 Placers exist in different types of sedimentary deposits (fluvial, marine, eolian, etc.), although they all
 originate from lode deposits. Most of the gold placers mined in the U.S. are of fluvial origin.  Placer
 deposits are typically found in unconsolidated sedimentary deposits,  although depending on the nature
 of the associated materials, placers may be cemented to varying degrees. The terms pay streak, pay
 dirt, and pay gravel refer to the zone where the economic concentration of gold is located.  This layer
 is often found adjacent to the bedrock. Finer gold particles are carried farther from their source and
 have a greater tendency to be distributed throughout the sediments in which they are found.  The
 value of the pay streak is usually assessed as troy ounces per cubic yard, and varies throughout the
 deposit (Boyle, 1979).

 The density of gold, and its resistance to weathering, are the two principal factors for the
 development of placer deposits. Gold is considerably more dense that the minerals typically
 associated with it (19.13 grams per cubic centimeter (g/cc) versus 2.65 g/cc for quartz).  Heavy
 minerals typically settle to the bottom of a stream or beach, displacing lighter material in the process.
 Gold continues a downward migration in response to additional agitation in the streambed.  Settling
 action also occurs on land hi colluvium although the downward migration is not as pronounced hi the
 absence of a fluid matrix. Placer deposits are formed as particles accumulate hi this manner (Park
 and MacDiamid, 1970).

At a typical placer mine, overburden is removed and ore is blasted to fluff-up the material and make
it easier to excavate. The ore is then hauled by trucks to a wash plant, which consists of a
combination of equipment used to size and concentrate the ore. A typical wash plant consists of a
grizzly and/or a trommel, where sizing takes place. The ore is then  washed into a sluice, where the
gold (and other heavy minerals) settle below the riffles and onto matting.  The gold remains hi the
sluice,  while the tailings and wash water flow out of the sluice and into a tailings or settling pond.
                                             3-57                              September 1994

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IIIIIIM^ IIIIIIIIIH    Illlllll i 1 H  111 Ililllllllllllli II 'I Illlllll^    Illllll Illlllll Illlllll II Ililllllllllllli il IliiH^ II Illlllll 111 111 111 I 111 111 11  111 Illlllll 1 Illlllll 11111 Ililllllllllllli  1 111 li 111 II Illlllll IP Illlllll IIIIH^^  Inlll 1 Ililll Illlllll I 111 III III11III1 111 '  11111
                                                                                                    Ililllllllllllli l|illlillHii|llilH    Ililllllllllllli I PI
             Overview of Mining and Beneficiation        _ EIA Guidelines for Mining
                             .  IIIIIIH  Illlllll III Illllll I Illlllll Illlllll 1 1 IIIIIIH    III II I Illlllll I II 111 •Ililllllllllllli Illllll 111 11111 Ililllllllllllli   '       1 1 II  1111 III    I l 1   Mill    II  I  '     I   I i  Illlllll
            Periodically (every 1-2 days), the wash plant is shut down and the gold is removed.  The concentrate
            may then be subjected to further, more refined concentration, with gravity separation techniques such
            as jigs, shaking tables and pinched sluices, and possibly magnetic separation, if magnetite is present,
            to produce a high grade concentrate suitable for processing.
                i [[[ : ..................... ' ......... : ............    ,      '   ,   • '  '•      •     ' i  '       •'• ..............  :"'"; ........
            333.1    Mining          '        "' ........ • [[[ ! .......... '• .............. '. [[[
                i   , •  ,       ,    ;                      ^       ' .        '          ^      " i      '         •    '
            Extraction methods employed at gold placer operations differ, substantially from hardrock extraction
                    .  Large amounts of overburden, waste rock,  and ore must be excavated and concentrated to .
                                   —   —  —
                  ..... gjjj ..... pjacer mines ....... is ...... high, ........ sometimes ...... as ...... high as 10:1. ............. In ..... toe coldest ..... regions where gold '
                  !!!!"!"§ ...... i^c£m^» ....... S^^Sl^^^iconsisting of vegetation, ....... muck, ....... and ..... waste ...... rock) and ore
                 _ ^__^ _ j^^^j -y blasting and/oj. mechanical means prior to extracting the ore. They may
                    	,	                  ^     	                '
                    extraction at placer operations may be conducted using either surface or underground
                    "»	to*	55^5,	5E§!5ds	52	m,2§!	commonly used because they generally are the least   '
                               » i??0):  Jhe principal surface extraction method is open cut mining.  Other
                                                                                .
                     .SSSKxk	employed at gold placer mines include dredging, hydraulickhig, and other
                           small-scale	extraction techniques, such as panning and small suction dredging.
           Gently, use of dredging and hydraulicking methods is limited in the United States.  Underground
                  methods include bore-hole and drift mining.  (Alaska Miner's Assn., 1986; Argall, 1987)
          1987).
                    ™!J!Fg "^yes stripping away vegetation, soil, overburden, and waste rock to reach the
                    ..... below. ..... ,, ..... IMpay ore is blasted if necessary and can be excavated by bulldozers, loaders,
                     Si ..... f2iS2Sa ........ SSSESS ...... 2£ ..... SHElS ...... .&S2 ..... S2Ssport the ore to a wash plant"" for' beneficiation. '
                  ..... 2£ ...... fSSSSSa ..... ^^^^^^^SS^S^ ...... *** ..... ™& Plant, and me direction of the
                  activity is awayr:frpm ..... Ae plant. ^Once a cut has been mined,  it is generally either backfilled
               excavated overburden and waste rock or converted to a water recycle or sediment pond (ADEC
          Dredges are used hi both surface mining and underwater mining of placer deposits, but are generally
          ass0cifed wira *e mining and beneficiation of metal-bearing minerals (yalues) below water level.
                                ..... I* ..... SBlilliy , of a saturated placer gold deposit or the existence of a water
lllllll Ililllllllllllli
                                              ,
          table near the surface to create the appropriate excavating environment (i.e., a pond).  Four

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.  EIA Guidelines Tor Mining	-	Overview of Mining and Beneficiation

  is generally a sluice box. The pressurized water jet can also be used to thaw frozen muck and to
  break up and wash away overburden. This is generally not used today, having been outlawed hi most
  jurisdictions. However, hydraulic removal of overburden may still be practiced at a few mines
                             * *                                           H
  Small-scale extraction methods include panning and suction dredging.  Panning is a low budget, labor
  intensive method involving fairly rudimentary gravity separation equipment.  Panning is also a
  sampling method used by prospectors to evaluate a placer gold deposit to determine whether it can be
  mined profitably.  Small-scale gold placer miners also use a variety of other portable concentrators,
  including long loins, rocker boxes, and dip boxes (EPA, 1988a). Small suction dredges are used by
  recreational or small (part-tune) gold placer ventures. A pump varying from one to four inches
  usually floats immediately above the mined area. The mechanism that  recovers the gold sits hi a box
  next to the suction pipe and is carried under water. Alternatively, the nozzle has two hoses, one that
  transports water to the head and the other that transports material to the surface of a beneficiation
  device (i.e., usually a small sluice box that deposits tails back into the stream).

 Drift mining and bore-hole mining are terms applied to working alluvial placer deposits by
 underground methods of mining.  Drift mining is more expensive than  open cut sluicing and
 hydraulicking, so it is used only hi rich ground. In drift mining, the paystreak is reached through a
 shaft or an adit.  Ore that has been separated from the vein either by blasting or with hand tools is
 carried hi wheelbarrows or trammed to small cars that transport the gravel to the surface for
 beneficiation. If a deposit is large, then regular  cuts or slices are taken across the paystreak, and
 work is generally performed on the deposit hi a retreating fashion from the inner limit of the gravel
 (DOI, 1968; Argall, 1987).           .                 .

 3.3.2.2    Beneficiation

 Beneficiation of placer ores involves the separation of fine gold particles from large quantities of
 alluvial sediments. Gravity separation is the most commonly used beneficiation method.  Magnetic
 separation is used hi some operations to supplement the gravity separation methods.  Water is used hi
 most, if not all steps to wash gold particles from oversized material and then to move ore concentrate
 through the wash plant.  For land-based operations,  the plant may be stationary but is often mounted
 on skids so that it can be moved along with the mining operation as it progresses.  Dredge operations
 frequently employ floating wash plants, where the beneficiation equipment is carried within the
 dredge.

 Beneficiation typically involves three general steps:  the first is to remove grossly oversized material
 from the smaller  fraction that contains the recoverable gold; the second is to concentrate the gold; and
 the third is to separate the fine gold from other fine, heavy minerals.  The same type of equipment is
 often used hi more than one step.  For example, an array of jigs may be employed to handle
 successively finer material (Flatt, 1990).
                                             3-59                              September 1994

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               I	!"      •  •   '"	•*•'•••:•'•   •   "•""  •""  -    '   '	   ""  :  '	  '  :I '"'I	;    •    •' •      :  "
                            i,                          •                        i,         '         ,
   It                        "
                                                                                     '   i

	 Overview of Mining and Beneficiation	•	               E3A Guidelines for Mining
               t       "      	    •        .        .                . •  •                  I
             Classification (sizing) is the initial step in the beneficiation operation when the large, oversize material
          	X«s5aHy	Over" 3/4	|5J)	g	JJnioved	duringlieneficXrf^	A	rough' (large "diameter)' screen is" usually
             used.  This step may be fed by a bulldozer, front-end loader, backhoe, dragline or conveyor belt.
             Within the industry, this step is also referred to as roughing (EPA, 1988a).  The  ore is then subjected
          	fp^a	coarse	conc^njratfon	stage.  This step, referred to as cleaning, may employ trommels or screens.
             Other equipment used in the coarse concentration stage includes sluices, jigs, shaking tables, spiral
             concentrators and cones. Depending on the size of tie gold particles, cleaning may be the final step
            in Dcneficiation (Flatt, 1990; Silva,  1986)^	.'	"	
                            i     '                                              '         I' i                    '

            Hpe, ..... cooceotration ig ...... the ...... final ..... operation used ..... to remove | very small gold values from the concentrate
         WngiaafenBed in the previous stages.  Many of the previously identified pieces of equipment can be
            calibrated for finer separation sensitivity.  Final separation uses jigs, shaking tables, centrifugal
            concentrators, spiral concentrators or pinched sluices.
                            ' '• •    ,                    '           "             •  ' .;|,i        I '   "        '
             •   !                !               "'","'.        ;        ••">    .    i1   '•  "   . "'    •  "'
            333,3    Wastes and ..... Management Practices  '

            Mining and beneficiation wastes associated with gold placer mining include tailings and water used
            for beneficiation. Mp|t of these materials are either disposed of at the mine site (overburden and/or
            tailings), recycled during the active life of the mine (water), or used for onsite construction material
            or reclamation concurrently with mining or after operations end (overburden and/or tailings). Large
            amounts of overburden or waste rock are associated with placer mining. Because the desired material
IB sfH;s ' 'i,!!!!,!!: is such a small fraction of the material mined' (<  0.1 troy oz/ton) there is a tremendous amount of
            waste rock generated. Then, large amounts of water are used to process the material.  The type,
            volume, and characteristics of the wastes resulting from gold placer mining, as well as the waste
           .management units associated with these wastes are discussed below. (Again, the use of the term
            "wastes" is not intended to identify materials that are "solid wastes" under RCRA.)
iiiiii|iiiiii iiiiiiiii 1 1 • ( i ii n n                                 '                                     '
                                                                                i       n
           Waste rpck is generally disposed of in waste rock dumps near the point of excavation.  Eventually,
           the stockpiled waste rock may be used to backfill the mine cut  during reclamation.  Surface mining
           operations generate more waste per unit of  crude ore extracted  than underground operations, although
           stripping ratios vary from one site to the next." Overburden removed from the mine cut is stored
111 IIIIIIIII 1111 1 III II III 111 I IIIIIIIII IIIIIIIII I          _    ^mil 111111 111 Illllin^    IIIIIIIII III I IIIIIIIII 111  •                                         o»vriWM
           p nearby, sometimes piled along the edge  of the pit until mining  ceases, at which time it is used to
           backfill the cut.
                      %                     •            .           .                                      „ ,
                                                                                -.,,       ;        i        i;
           Wastes from gravity concentration operations  consist of a slurry of gangue (non-gold material) and
           process water that passes through tie ...... ^^j^g^ ....... ope^tionT ............ Tailings 'are ..... dassified ..... by ..... their ...... size
           into three classes:  coarse or oversize tailings, intermediate tailings (nuddlmgs), and fine tailings
           (sl™ps)-  Of the three grades delineated, fine tailings can be further broken down into two categories.
 ••™w''l' ..... Components of the slurried tailkigs can be classified as settleable solids, which are made up of sand
                                                        3-60                              September 1994


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 EIA Guidelines for Mining                    .            Overview of Mining and Beneficiation

 and coarse .silt, or as suspended solids, composed mostly of fine silt and some clay size particles.
 (EPA, 1988a)

 Large volumes of flowing water are used to cany the ore through the classification operation.  The
 velocity of the flowing water generates a large volume of intermediate and fine tailings in the form of
 suspended sediment and lesser quantities of dissolved solids.  Historically, the water and sediments
 were released to streams and created problems downstream from the mining sites. Currently, release
 of sediment is controlled by using impoundment structures where the water is held and the velocity is
 consequently reduced. As flow is restricted, sediments are deposited. Exposure of waste rock and
 ore during mining and beneficiation greatly increases the likelihood that soluble constituents will be
 dissolved. Once in solution, dissolved solids are much more likely to pass through sedimentation
 structures and reach surface waters.

 Recycling or recirculating water at gold placer mines reduces the volume of effluent to be discharged
 after treatment.  Production statistics from  1984 show that 21.3 percent of the Alaska gold placer
 mining industry achieved 90-100 percent recycle of the process wastewater (Harry and Terlecky,
 1984a).  Operations that separate oversize tailings prior to sluicing typically use less water than mines
 that  do not classify the excavated material (Harry and Terlecky, 1984b).  Where classification
 methods are used, approximately 1,467 gallons of water per cubic yard of ore are needed, whereas at
 mines-that do not classify material, average water usage is 2,365 gallons per cubic yard of ore (EPA,
 1988a; ADEC, 1987). The Clean Water Act effluent limitations guidelines for placer mines (40 CFR
 Part 440, Subpart M), promulgated  in 1989, generally require recycling of process wastewater and
 have reduced the total discharge of wastewater from placer mining operations.

 Chemicals are not typically used during beneficiation at placer gold mines, so tailings contain the
same constituents found in the extracted ore.  Potential natural  constituents of gold placer wastes
include mercury, arsenic, bismuth, antimony, thallium,  pyrite,  and pyrrhotite.  These are often found
 in discharges from placer mines.
                     .-
                                                     *
Waste and non-waste materials generated as a result of extraction and beneficiation of gold placer ore
are managed (treated, stored, or disposed) in discrete units. These units  are divided  into two groups:
(1) waste rock piles and (2) tailings  impoundments.

In general, the goal of treating or managing waste streams of gold placer mines is to separate the silt
and fine-grained solids from the water, reusing the water or ensuring it meets NPDES discharge
requirements prior to  discharging to a stream.  Most waste management occurs after sluicing; die
 stacking  of overburden and waste rock in areas proximate to the mining operation, however,
 constitutes an interim method of managing the materials prior to their ultimate return to the mine cut
 (Alaska Miner's Assn., 1986).
                                             3-61                               September 1994

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                                                          in in in in 11 iiiiiii ill 1 in iiiiiii iiiiiii 11 iiiiiiiiiiiiiiii in 11 Hill i iiiiiiiiiiiiiiiliiiiliiiiiiiiiH    iiiiiiiiiiiiiiiiiiiiiii
  I lllllllllllllll|llllllllll  P'M IIIIIII III III           IIIIIIH     III IIIIIII I IP III III i in IIIIIII  III In I III III 111 III II 111 III  1 I I II  I lllllll I III illlllilllilllil III I lll| 111 111 111 lllilll III I III llll III 111 III lllllli III  1 lllllll III lii'in
                          *
         Ofgijgw ...... of,,MMng and Benefication             _    EIA Guidelines for Mining
                        '              """" ~ ~ ~ "* ~~ ~ """ *"*** **"*
I lllllll
                                                                   ..
       SIS SS2 Hays to maximize the quality of the effluent discharged from a gold placer operation.
Tbg^are ..... used ...... separately ...... or, ........ increasmgly ...... frequently, ....... together. The effluent can be .treated, using a
variety of impoundments (tailraces, pre-settling ponds, and settling/recycle ponds), filtration, and, in
rare instances, flocculants. The mining operation also can be modified to reduce water use during
beneficiation, thereby reducing the volume of effluent discharged. Waste, management methods used
to achieve this reduction include classification^ recycling, use of a bypass, and control of water gain
     .....      " .....    ......  -       ...... ,—~ ...... _™,™__ ....... «._,, ......... —..     ............    ..............  _  ,
        •*                *                                              "             i
        Tailings are typically disposed of in impoundments or used for construction.  The method of tailings
        disposal is largely determined by the water content of the tailings.  Tailings impoundments associated
        with gold placer mines are generally unlined containment areas for wet tailings. At most gold placer
        opetittfons, the disposal of tailings requires a permanent site with adequate capacity for the life of the
        mine.  The size of tailings impoundments varies between operations, however, if the impoundment is
        going to function effectively, the dimensions and characteristics are tailored to meet the specifications
      i  fora paiticular operation.- -•'•••-

       Tailraces and pre-settling ponds are characteristic of open cut surface mining operations.  Even at
       open cut mines, however, there are variations of the typical tailrace and pre-settling pond.  Two pre-
       settling ponds are sometimes used simultaneously and in series to provide extra storage hi case die
       first pond fills prematurely or in the  event that a scheduled  cleaning is missed. Alternatively, two
       parallel pre-settling ponds might be used at alternating times.  (Alaska Miner's Assn., 1986; ADEC,
       1987)  Settling ponds are similar in form and function to tailings impoundments and are used
      primarily by large-scale placer operations. Settling ponds are usually created by constructing a dam
      composed of tailings across the downstream end of the mined cut When.the next cut is mined, most
      °f 1^?, 55?¥^,,§**lllStt Is captured  hi this new pond. Thus, as mining progresses, a series of ponds
      emerge.
      3.3.2.4    Environmental Effects

      Most environmental effects associated with placer mining activities concern water quality.
      Historically, the most severe impacts have been physical disturbances to stream channels and the
      addition of large quantities of sediment downstream.
                  initiation of any regulatory controls, little or no effort was made to recpntour waste rock
      piles to resemble premming topography.  Natural revegetation of historical placer grounds from
      Alaska to California ranges from none to complete. Depending on the remaining substrate, natural
      fSSSi	I55555	II	I°!Si	,§?,£§§	53?y ^e a century to return to premining condition.  These operations
      were also responsible for generating large quantities of sediment and increasing concentrations of  .
      bsavy metals, including arsenic, copper, lead,'and mercury, downstream from mining activities
      (ADEC, 1986; Clark, 1970;	HMniesi	1981)!	'"
                                                    3-62                              September 1994

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   EIA Guidelines for Mining   	        Overview of Mining and Benefication

   A 1985 Alaskan field study indicated that total suspended solids were elevated in a number of actively
   mined streams. During this study, sediment ponds were employed at some operations and provided a
   wide range of effectiveness.  Downstream uses such as water supply, aquatic life, and recreation were
  precluded as a result of the increased sediment loads in two of the three streams studied. Fine
  sediments were readily carried downstream in response to increased stream flows (spring runoff),
  therefore the severity of localized impacts could change with time as sediments were picked up and
  redeposited in different locations downstream (ADEC, 1986).

  The same study found mat total dissolved solids were  not categorically increased as a result of mining
  activities although levels of iron, manganese, cadmium, mercury, copper and arsenic were elevated
  below mining operations in some streams. (It  is not clear from the study whether these concentrations
  are expressed as total or dissolved).  A study of water quality within the Circle District,  Alaska,
  conducted in 1983, showed elevated levels of total arsenic, copper, lead, and zinc, and elevated levels
  of dissolved arsenic and zinc  downstream from placer mining activity.  Mercury and cadmium levels
  were not elevated downstream from mining.  Concentrations of dissolved constituents are typically of
  more concern in terms of water quality as the dissolved fraction is available for uptake by living
  organisms (ADEC, 1986; LaPierriere, et aL, 1985).

 The physical locations of placer mining activities and wetland ecosystems often overlap.  Mining
 activities, particularly those mining recent alluvial deposits potentially impact wetlands directly during
 the removal of vegetation and soils or indirectly by  removing or rerouting the hydrologic regimes that
 support  wetland hydrology. Operators impacting wetlands are required to obtain a Clean Water Act
 Section 404 permit, and comply with Section 404(b)(l) guidelines.

 Wildlife may also be impacted by placer mining through the physical disturbance of stream channels,
 the addition of sediments to streams, and the presence of human activities and heavy equipment in
 what are typically remote areas. Mining presents a physical barrier to fish migration through the
 disruptions diversion of active stream channels. Sediment concentrations in streams can result in
 gffl damage, reduced fertility,  and changes in blood chemistry, and reproduction may be inhibited or
 precluded when spawning grounds are lost to siltation and eggs are suffocated when covered by
 excess sediment (ADEC, 1986; Reynolds, 1989).

 3.3.3    LEAD-ZINC

 In 1990, there were a total of 29 lead/zinc mines operating within the United States. Of these 29
 mines, 16 produce both lead and zinc; two produce lead but not zinc; and 11 produce zinc but not
 lead.  In 1990 alone, these mines produced 495,000 metric tons of lead concentrate (making the U.S.
 the world's largest primary producer) and 515,000 metric tons of recoverable zinc. For the same
year, employment figures were estimated to be 4,500 workers at  mines and mills and 3,300 at
secondary smelters and refineries.  Twenty-one of the mines are located west of the Mississippi, in
                                             3-63                             September 1994

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             Overview of Mining and Benefitiation
                                                                         EIA Guidelines for Mining
                States of Missouri (9 mines), Idaho (3), Alaska.(2), Colorado (2), 'Washington (2), Montana (1),
                 Mexico(1), and Oregon (1).  The remaining eight mines are located in Tennessee (5 mines) and
            New York (3).
    :I| ...... | ......  || ..... P™S|y ...... £2 ..... S25ES5SS ..... Jfid
                             ...... percent ..... » ..... iMJl
                                                         ...... CZO percent) in batteries,- fuel tanks, solder, seals,
                                                                  e^^
!^!!^!!Mj^^OT, and other industries.  U.S. and world	demand	fe Jeclinedjn	recent years, in large part
SBS&j^!^	!?,	22H5HM	concerns.	Z|ne,	Js	isgl	|n galvanizing (53 percent), zinc-based alloys  .
[[[                                                .....
l=~™r®? J=j==ik brass ^ br°nze <14 percent), and for other purposes.
                                                   m	indergj;ound_pperations,	although a few surface
                         tist. The decision to use underground or surface mining techniques is dependent on
      	*S.!ffiSS	££?.«££&	2	22	ZS2;,,	£SSS5S&&to*	.techniques are commonly used to   '
           extract lead-zinc are from large, flat^ymg, Jabular-,shaped, strata-bound deposits. In contrast,
                                                •deposits	isTjest	^tedjojnare	selective,stope mining  .
                                                              y the i
                                                                                                   I	Hill	11(1	II	I	Ill III III
                                                                                                 II  II  I   III III 11 II III
       »'	•	"	is	     •   	s&Bfflsss	,£i:!!::a	      	\	'"'''""'""'''	''
                     ! ofjeadjnnc§155 ranges from as low as three percent metal in ore for large, easily
          	.]	SSjjjjjS	£51522	f°£,	SS3L	£Sto!&&aSSSa&	underground mines, to more than 10
           for extremdv .high-cost.remote,,,,,areass I^w grade lead and zinc ores can also be mined
   y^^ when Produced as a byproduct of copper mining, or when appreciable quantities of preci
                                                                                                    ous
      i^S£	SS	£	Illlt	S	ESS!	fffSS	JS&k	Few,!e§d3|nc	deposits contaui more than 50
              s%± tons of ore.
              	iliiioiw^          	':':!.i!lj«^
                                                                       PH. in	iiiiipii; i	PI iiiiiiiiiiiiiniiii11 'iiiii'	pii	up1"	iiliiiiiininipiiiiiiiiiipppigiiiiii piinipi liiiiiniiriiii iipin
                                                           .'•in	pi1:!.:.!	PIIIII PII',HI:	IP 'ipiuip
                                                                                                     JP.IIII;. i	P4p,n ;IJH^
         _	           ,     iiiiiii	IIIM^^^^^^^^^^^^           	::IK«           	IK             	ii^  	ill!	i'ii'^ifiiiii.:^	i^'tiiifs      	mx	i	ii
          Benfificiafion nf \i^>A unA •»?«/» M^«« :<. » *t.___ _*.	            .  .    .
                                            S iSS&sjep process consisting of milling, flotation, and
|93S!yi[€|f£og	(Bureau	oLMinegj	1984c	and, 1985).
                                                   1900s,, gravity concentration was the chief
                                                    owever, with more selective reagents and
                                                   tu^                              Gra
                                              M§ed ...... for preconcentrating before fine grinding and
                                nc ..... ores,,,were concentrated. .However, with more selective reagents and
                                             o:,,,v|rtu^                              Gravity
                             	                  .
                             it lip                   	(iH^^      	{''ifii:	 .               	i!	tmi4:ii',	iipfhi^	!«i
           Uli	Slip	gjj	|5igi|iii2i	2EE!!25	dLSS&SS and grinding. Crushing is usually a dry
                  	221	=22	SgraI5	™?y .*?	??ntrol ^dust.' Frequently, a primary crusher Qaw crusher) is
               4j	le:	S»ne;	site, to	^reduce	the	ore	material	into	particles less than 150 millimeters (mm) (6
                                                                                            iilllliM^
                                                                                                                   ^^ 	iliil
	;	'	' ''	is	'"'	*3~O^

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  EIA Guidelines for Mining	         Overview of Mining and Beneficiation

  inches) in diameter. The crushed ore is then transported to a mill site for additional crushing,
  grinding, classification, and concentration.

  Additional milling uses a cone crusher, usually followed by grinding in rod and ball mills.  Grinding
  is a wet operation in which water and initial flotation reagents are added to  form a slurry.
  Alternatively, the ore may be fed into an autogenous mill (where ore itself acts as a grinding medium)
  or a semi-autogenous mill (where the ore is supplemented with large steel balls).

 Between each grinding unit operation, hydrocyclones are used to classify coarse and fine particles.
 Coarse particles are returned to the mill for further size reduction.  The resulting size of the classified
 ore is; usually about 65-mesh (6.3 mm).  Chemical reagents that will be used during flotation
 separation activities may be added to the ore during milling activities (Bureau of Mines, 1985 and     •'
 1990a). .Mill production capacities can be as high as 7,000 to 9,000 tons per day.

 Flotation                         ,

 Flotation is the most commonly used technique to concentrate lead-zinc minerals.  Several separate
 flotation steps may be necessary to Jbeneficiate these polymetallic ores. Most sulfide ores contain
 varying amounts of minerals such as lead, zinc, copper, and silver; thus, multiple floats are needed to
 concentrate individual metal values (Bureau of Mines, 1985a; Weiss, 1985).  The tailings (residual
 material) from one mineral float are then used as feed for a subsequent float  to concentrate another
 mineral.  A typical example includes the following steps (Fuerstenau, 1976):

      •   Bulk flotation of lead-copper minerals

      •   Depression of zinc and iron minerals using such chemicals as sodium sulfite and zinc sulfate

      •   Flotation of a copper concentrate

      •   Rejection of a lead (sink) concentrate using sulfur dioxide and starch

      •   Activation and flotation of the sphalerite (using copper solution) from iron and gangue
          minerals

     •   Flotation of pyrite, if recovery is desired

     •  Flotation of barite concentrate.

The froui recovered  in each of the cleaning cells is transferred to thickeners,  where the concentrate is
then thickened by settling. The thickener underflow (the concentrate) is pumped, dewatered by
passage through a filter press, and then dried.  The liquid overflow from the  thickener contains
wastewater, flotation reagents, and dissolved and suspended mineral products.  This solution may be
recycled or sent to a tailings pond (Fuerstenau, 1976).
                                             3-65                               September 1994

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                                 lllllfl	Ill	IIP	ill	I'llilM    	I	("Ill	i'lilltliilllll	1	1	Ilill	ill
                                                                                             .                  .
            ""Overview of Mining and Beneficiation
EIA Guidelines for Mining
            Wastes from the various cells (typically rougher, scavenger, and cleaning cells) are collected and
            directed to a tailings thickener.  Overflow from this unit (wastewater containing high solids and some
            wasted reagent) is often recycled back to the flotation .cells.  Thickener underflow (tailings) contains
            remaining gangue, unrecovered lead-zinc material, chemical reagents, and wastewater.  This
            underflow is pumped as a slurry to a tailings pond.  The solid content of the slurry varies with each
            operation, ranging from 30 to 60 percent.
                |l"l           '                ' '                 '  .              .',..!
                I             	            Ill       J                       '                             ' ' ''
            Sintering
            Concentrates of lead and zinc minerals that are to be processed by pyrometallurgical methods, such as
            smelting and refining, may require sintering, depending on the processing methods used.  Sintering
            'llflgf                                       .        iiiiiii iiiiiiii Hill iiiii iiiiiiiii in iiiiii iiiiiiiiiii i iii iiii iiiiiiiiiii 11 iiiiii iiiiiiiiiiiiiiiiiiii i ill 111 in i in in iiiiiiiiiiii i 11
            operations consist of several steps, including blending, sintering, codling,  and sizing. Raw materials,
                                                        '	'	U     tJreeze are
           blended with small amounts of moisture in pug mills, balling drums, or balling pans.  The concentrate
           feed is men fired (sintered) .and cooled".  The suiter is crushed during cooling and is typically less than
           six inches in diameter. This product will be graded and further crushed in some operations to
           produce a smaller sinter product (Weiss, 1985).  Four of the five primary lead processing facilities in
           the United States sinter the concentrate prior to processing.
                      Wastes
                i                                                                         I
           Wastes generated by lead-zinc operations include mine water, waste rock, tailings, and refuse. Many
           of these wastes may be disposed of onsite or offsite, while others may be used or recycled during the
           active life of the operation.  Waste constituents may include base metals, sulfides, or other elements
           found in the ore, and any additives or reagents used in beneficiation operations.   The primary waste
           generated by underground mines is mine development rock, which is typically .used in onsite
 ,   	Lin ,i W construction for road or other purposes.  Surface mines usually generate large volumes of overburden
	[and waste	rock	that	arg	usually;	disposed of in waste rock dumps.  (As before, "wastes" discussed
           here are not confined to RCRA solid wastes.)
                                 !'                            '         •                   [
                                       '                                                  i
           Overburden and Mine Development Rock
                                                 5M5PS include overburden and mine development rock
                              to as waste rock.  As noted previously, the materials can be used onsite or placed
             waste rock dumps. The quantity and composition of waste rock generated at lead-zinc mines varies
             	|'|||"||	I	||	''III!!!!!!!!!!!!!!!!!!!,!!!!!!!!!"!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !1!!!!!!!!!!!"!!!!!!!;!!!!!!!!!!!!,!!,!!'!' I!!!!!!!!!'!:!!!!!,' I!!!!!!!!!!!!!!!,!!!	I!!,!!, ,!!!!!!!!!!,,!!!1!! I!!!!!,,!!!!!!!!!!!!!!!!!!!::!!!!!!1!1'!!!!!,!!!' „„!!!''"!:	;	;	;	„	:	:,:	:	a,	s	:	i	i	i	\	:	:„:	i:	
              *tly_	bejEES!	sites.	These,	.wastes	wjll	.contain	mmeralg	a§sp5cjated	wjjjjj	jjjg	pie	body andi host rock.
                  minerals associated with sulfide ores are chalcopyrite, pyrite,  calcite, and doloniite (Weiss,
                                                  ;,.. ^I:MM^^^         	KM	W:T«IB^^^^^^^^^^^^^^^
                                                                                    	\	September 1994

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  EIA Guidelines .for Mining	'    	    Overview of Mining and Beneficiation

  Mine Water

  Mine water consists of all water that collects in mine workings, both surface and underground, as a
  result of inflow from rain or surface water, and groundwater seepage. As necessary, water may be
  pumped from the mine to keep it dry and allow continued access to the ore.  The pumped water may
  then be used in beneficiation, pumped to tailings ponds, or discharged to surface water. The quantity
  and chemical composition of mine water varies from site to site, depending on the geochemistry of
  the ore body and the surrounding area.  Mine water may also contain small quantities of oil and
  grease from extraction machinery and nitrates (NO3)  from blasting activities. Based on studies of lead
  mines in the United States, the range of concentrations in mine water (mg/1) for lead was 0.1-1.9,
  zinc 0.12-0.46, chromium 0.02-0.36, sulfate 295-1,825, and pH 7.9-8.8.  After the mine is closed
  and pumping stops, the potential exists for water exposed to sulfur-bearing minerals in an oxidizing
  environment, such as open pits or underground workings, to acidify.  This may lead to the
 mobilization of metals and.other constituents in the remaining ore body exposed by mining and to the
 contamination of surface and/or groundwater. Alternatively, flooding of underground workings can
 reduce exposure of sulfide minerals to oxygen and effectively eliminate acid generation.

 Flotation Wastes                                       '    .

 After the removal of values in the flotation process, the flotation system discharges tailings composed
 of liquids and solids. Between 1/4 and 1/2 of the tailings generated are made up of solids, mostly
 gangue material and small quantities of unrecovered lead-zinc minerals.  The liquid component of the  .
 flotation waste is usually water and dissolved solids, along with any remaining reagents not consumed
 in the flotation process.  These reagents may include cyanide, which is used as a sphalerite depressant
 during galena flotation.  Moist operations send tailings to impoundments where solids settle out of the
 suspension. The characteristics of tailings from the flotation, process vary greatly, depending on the
 ore, reagents, and processes used.

 Chemical Wastes

 In addition to wastes generated as part of extraction and beneficiation, fadlities also store and use a
 variety of chemicals needed for mine and mill operations.  A list of chemicals used at lead-zinc mines
 is provided in Exhibit 3-8.

333.4    Waste Management

Wastes generated as a result of mining and beneficiating lead and zinc minerals are managed (treated,
stored, and/or disposed) in discrete units—waste  rock piles or dumps, mine pits and underground
structures, and tailings impoundments.
                                            3-67                              September 1994

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             Overview of Mining and Beneficiation
                                                                                  EIA Guidelines for Mining
                  lllllll 111 111 111 III II Illllllllll IIIIIIM^  Illlllllllllll  lllllll 111 Illlllllllllll lllllll III IIIIIIIIIIIIIB     111 II Illlllllllllll 111 II 111 I Illlllllllllll 111 II  III Kill 111 I lllllll II Illllllllll Illllllllll 111 lllllll 11 Illllllllll Illlllllllllll 111 I ll|lll|l II
111	•
   Illlllllllllll Illllllllll
                                    Exhibit 3-8.  Chemicals Used at Lead-Zinc Mines
                Acetylene
                Calcium Oxide
                Hexone
                Hydrogen Chloride  •
                Methyl Chloroform
                Methyl Isobutyl Carbinol
                Nitric Acid
                Propane
Sodium Cyanide
Sulfur Dioxide
SulruricAcid
Diesel Fuel No. 1
Diesel Fuel No. 2
Chromic Acid, Disodium Salt
Copper Solution
Kerosene
Methane, Chlorodifuoro-
Sodium Aerofloat
Sulfuric Acid Copper (2+)
Salt (1:1)
Zinc Solution
Zinc Sulfate
              Source: National Institute for Occupational Safety and Health, 1990.
           Waste Rock Piles
                                                                                       .  I  '
       *         i   i             i                                                 i        |     i    •
           Waste rock (overburden and mine development rock) removed from the mine is stored and/or
    ! Ill 111 lllllll disposed in nnlined piles onsite.  Constituents of concern in runoff and leachate from waste rock piles
           includes heavy metals.  These piles also can generate acid drainage if sulfide minerals and moisture
        1 Si1!!	are present in sufficient concentrations without adequate neutralization potential or other controls.
                I                          »

           Mine Fits and Underground Workings

           In addition to wastes generated during active operations, when the mines close or stop operation, pits
           and underground workings may be allowed to fill with water. This accumulating water, which may
           become mine drainage, can acidify through aeration and contact with sulfide minerals and become
           contaminated with heavy metals.  At pits where quartz minerals are associated with lead-zinc deposits,
          silica dust exposure may be a problem bom during mine operations and following closure. Asbestos
                               be	preseitt in pits where limestone and, dolomite ores are mined, may also be a
          minerals,w
	!	 _.	I.	^r *•
               gxi^y.S.	Department of Health and Human Services, 1982).
          Tailings Impoundments
                         5S ..... I§5§® .....
                       p£taiiijn|s ....... requires * P«rmaiMiit.she with adequate capacity for the life of the mine.
                                      to several hundred acres in size. The method of tailings disposal is

                                                            ; ,122, SEES!          "

                                                                                                structures
               !|;D«	used	to	construct,	a	gilings	pond:	water-retention dams	and	raised	embankments.  Water
                                    construction	of a dam, usually in a natural drainage area, and tailings
                                                                                topography to assist in
                            the dam.  The water retention
                        of tailings and tailings water.  A raised embankment is a phased approach to
                                    in which the, garjhen dam structure, composed of native soils, waste rock,
                                .™ successive lifts over the life of the project as need arises and materials are
                             .<	ii	mi	i	

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  EIA Guidelines for Mining	       Overview of Mining and Beneficiation

  available. Water retention dams are more costly but typically allow greater storage of process water
  and effluent in the impoundment.

  33.4    COPPER

  The physical properties of copper, including malleability and workability, corrosion resistance and
  durability,.high electrical and thermal conductivity, and ability to alloy with other metals, have made
  it an important metal to a number of diverse industries. Copper was an historically important
  resource for the production of tools, utensils, vessels, weapons, and objects of art.  According to the
  Bureau of Mines, in 1992, copper production was used for building construction (41 percent),
  electrical and electronic products-(24 percent), industrial machinery and equipment (13 percent),
  transportation (12 percent), and consumer products (10 percent) (Bureau of Mines, 1993a).

  The United States is the second largest copper producer in the world.  Next to Chile, the United
  States had the second largest reserves (45 million metric tons) and reserve base (90 million metric
 !tons) of contained copper in 1992.  United States' copper operations produced about 1.7 million
 metric tons in 1992.  In 1991, 1.63 million metric tons were produced. The total value of copper
 produced in 1992 was $4.1 billion^ Arizona led production in 1992, followed by New Mexico, Utah,
 Michigan, and Montana.  In the same year, copper was also recovered from mines hi seven other
 States (Bureau of Mines, 1993a and 1993b).

 The number of operating copper mines decreased from 68 mines in 1989 to 65 mines hi 1992.  Of the
 65 mines actively producing copper in 1992, 33 listed copper as-the primary product. The remaining
 32 mines produced copper either as a byproduct or co-product of gold, lead, Tine, or silver (Bureau
 of Mines,  1993b). Thirteen of the 33 active mines that primarily produce copper are located in
 Arizona; the remaining mines are located in New Mexico, Utah, Michigan, and Montana (Bureau of
 Mines, undated).

 In 1991, the top 25 copper producers in the United States accounted for more than 95 percent of the
 United States' domestic copper production.  These producers are listed in Exhibit 3-9 (Bureau of
 Mines, 1993b).

3.3.4.1    Geology of Copper Ores

Copper deposits are found hi a variety of geologic environments, depending on the rock-forming
processes that occurred. In general, copper deposits are formed by hydrothermal processes (i.e., the
minerals  are precipitated as suffides from heated waters associated with igneous intrusions or areas of
otherwise abnormal lithospheric heating).  These deposits can be grouped in the following broad
classes: porphyry and related copper deposits, sediment-hosted copper deposits, volcanic-hosted
                                             3-69                             September 1994

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             1   Overview of Mining and BeneScaation
                                                         . EIA Guidelines for Mining
        in hi i id'linn inn n i inn

             .
mini in iiiiiiiiiiiiiiiiiiiiini iiiiiiiiiiiiiiiiiniiiiiiiiii iiiiiiiiiiiiiiiiiiiiini
•1 iiiiiiiiiiiiiiiiiiiiiiiii1 ninnnnnniiiiiiinniiiiiinnnniniiniiiiinnnn
     111 111 Illilli1 III ill
HillIIIII1I Illllil	I	Ill
M^\l Illllil I Hill 111 I


llllllH


III IIIIIIIIIIIIIIIIIIIIIIIII 1111111111 I Illllill

IIH^^^^^^^^^^^^^
*










Exhibit 3-9. Leading Copper Producing Facilities in the United States
Bank
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
Y:'-.^Mfcie>K;$A:
Morenci/Metcalf
Bingham Canyon
San Manuel
Chino
Tyrone
Sietxita
Ray Complex
Bagdad
Pinto Valley
Mission Complex
Inspiration
White Pine
Continental
TwinButtes
Troy
SanXavief
Superior (Magma)
Miami
Casteel
Silver Bell
Lakeshore
Johnson
Oracle Ridge
Yerington
Mineral Park
County and State
Greenlee, AZ
Salt Lake, UT

Final, AZ
Grant, MM
Grant, MM
Puna, AZ
Final, AZ
Yavapai, AZ
Gila.AZ
Pima, AZ
Gila, AZ
Ontonagon, MI
Silver Bow, MT
Pima, AZ
Lincoln, MT
Pima, AZ
Final, AZ
Gfla,AZ
Iron, MO
Pima, AZ
Final, AZ
Cochise, AZ.
Final, AZ
Lyon,NV
Mohave, AZ
^ 	 	 -.is 	 :'J .... -'. in .' * •'," ••• 'I VV...V, ',"
Operator?!?-';1--;^:'./.':' "":<*••'• •"••: ';':
Phelps Dodge Corporation
Kennecott, Utah Copper Corporation
Magma Copper Company
Phelps Dodge Corporation
Phelps Dodge Corporation, Burro Chief Copper
Company
Cyprus Sierrita Corporation
ASARCO Incorporated
Cyprus Bagdad Copper Company
Pinto Valley Copper Corporation
ASARCO Incorporated .
Cyprus Miami Mining Corporation
Copper Range Company
Montana Resources, Inc.
Cyprus Sierrita Corporation
ASARCO Incorporated
ASARCO Incorporated
Magma Copper Company .
Pinto Valley Copper Corporation
The Doe Run Company
ASARCO Incorporated
Cyprus Casa Grande Corporation
Arimetco Incorporated
South Atlantic Ventures Ltd.
Arimetco Incorporated
Cyprus Mineral Park





                                                                           3-70
                                                                       September 1994
IM^^^^^
•                                     '                                                                    	ilinil

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  EIA Guidelines for Mining	Overview of Mining and Beneficiation

  massive sulfide deposits, veins and replacement bodies associated with metamorphic rocks, and
  deposits associated with ultramafic, mafic, ultrabasic, and carbonatite rocks.

  Copper occurs in about 250 minerals;'however, only a few of these are commercially important.  The
  most common sulfide minerals are chalcopyrite (CuFeSj), covellite (CuS), chalcocite (Cu2S), bornite
  (CujFeS^, enargite (CujAsS^, and tetrahedrite ((CuFe),2Sb4Si3).  Predominant oxide minerals are
  chrysocolla (CuSiOa), malachite (Cu2CO3), azurite (Ca^CO^OH)^  and cuprite (Cu2O),
  Chalcopyrite is the most common mineral found in porphyry-type deposits.  Chalcocite occurs
 predominantly in hydrothermal veins (U.S. Geological Survey, 1973).

 3.3.4.2    Mining

 Conventional open-pit mining techniques are the predominant methods used today by the copper
 mining industry, representing 83 percent of domestic mining capacity. In open-pit mining,
 overburden is initially stripped off to expose the ore. The waste rock and ore are excavated by
. drilling rows of 6- to 12-inch (diameter) blast holes.  Subsequently, large electric or diesel shovels or
 front-end loaders transport the ore onto trucks, trains, or conveyor belts for removal to milling or
 leaching facilities, depending on the type of ore (sulfide or oxide) and grade.

 The remaining 17 percent of the active copper mines use various types of high-tonnage underground
 operations. The three main underground mining methods used to mine copper ore are sloping, room-  •
 and-pillar, and block caving. Waste rock and mine water are generated by underground mining
 operations (as well as by surface mines).  See Section 34 for a broad  discussion of conventional
 open-pit and underground mining techniques.

3.3.4.3    Beneficiation

Beneficiation of copper ores and minerals can occur either through conventional milling and flotation
of high-grade sulfide ore or by leaching and solvent extraction/electrowinning (SX/EW) lower grade
sulfide and oxide ore.  The beneficiation method(s) selected varies with mining operations and
depends on ore characteristics and economic considerations.

Conventional Milling/flotation

The first step in the beneficiation of high-grade sulfide ore is comminution.  Typically, this is
accomplished by sequential size reduction operations—commonly referred to as crushing and grinding.
Crushing and grinding operations at copper mines are typical of those found throughout the mining
industry, including primary crushing in jaw or gyratory crusher (often in the mine workings),
secondary and tertiary crushing in cone crushers (typically in the mill), and grinding in rod and ball
or autogenous/semiautbgenous mills.  After grinding, ore is pumped to a classifier designed to
separate fine-grained material fless than 5 mm) from coarse-grained material requiring further


                                             3-71                              September 1994

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              Overview of Mining and Beneficiation
                                                                       EIA Guidelines for Mining
                                              111  , 111    lll|ll    I 111  111 111 III 111 111 I '   11)1111 111 111	II II II  Hull -I   II I 111 I 111
              grinding. The hydrocyclone is the standard technology for classification (Office of Technology
              Assessment, 1988; Taggart, 1945; Wills, 1981).
    iiimm	'

    1111 ¥'11111111.1! MIHIIOIPI
              The second step in the beneficialion of sulfide ore is concentration.  Froth flotation is the standard
              method of concentration-used in the copper industry for higher-grade ores.  About 70 percent of all
              copper is produced by this method. The ore is conditioned with chemicals to make the cooper
                1"' ;;       , "  	• ;!'	    ,i ;;|  „ ,              •            V   .        '; •     ' '• "• .     ' .  1 i. "''   ,    *,,*!
              minerals	water-repellent (i.e., hydrophobic) without affecting the other minerals.  Air is then pumped

              ttopHjghthe a^itate4 slurry to produce a bubbly from. The hydrophobic copper minerals are
              aerophillic; that Is, they are attracted to ah* bubbles, to which they attach  themselves, and then float to
                    '	of the cell.	^	As	they reach the surface, the bubbles form a froth that overflows into a trough
            ,	for collection.	The	other	noncopper minerals sink to the bottom of the .cell.  Following copper •
             recovery, molybdenum	(as" molybdenite" JMoSJ) and other' metals may then be recovered by selective '
            	i	;	;;„;	;;	;ili|	;	•	     * *      •    - • »  ,  •     *
             flotation	before	the slurry is disposed of as tailings.-

                                                           in inn viiiiiiiiii iiiii iiiiii uiiii ii
             Conventional flotation is carried out in stages.  The purpose of each stage depends on the types of
            " minerals	in the	ore.	Selective	flotation	of chalcocite-bearing sulfide ores and the rejection of pyrite
             utilizes three types of flotation cells:  roughers, cleaners, and scavengers. Many copper mills now
             also include column flotation to further enhance product recovery after scavenger flotation.  Reagents
             used in flotation concentrators at copper mines include collectors, depressants, activators, frothers,
             flocculants, filtering aides, and pH regulators. A list of the reagents typically used hi a copper
             flotation circuit is presented in Exhibit 3-10 (Biswas and Davenport, 1976; Bureau of Mines, 1987).
    ,
•W^
                                         Exhibit 3-10. Copper Flotation Reagents
Collectors
      Ethybcantnate
      Amylxanthate
      Isopropylxanmate
      Isobutylxanthate
      Unspecified xantbates
      Alkyl dithiophosphate
      Unspecified dithiophosphate
      Xanthogen formate
      Thionocarbamate
      Unspecified sulfide collector
      Fuel oH
      Kerosene
Depressants
      Phosphorous pentasulfide
      Cyanide salt
      Sulfide salt
      Sodium silicate
 Activators
      Sodium sulfide or hydrosulfide
 pH Regulators
      Lime
      Sulfuric acid
      Caustic soda (NaOH)
 Frothers •
      Aliphatic alcohol
      Pine oil
      Phenol
      Polyglycol ether
      Unspecified polyol
 Flocculants
      Anionic polyacrylamide
      Nonionic polyacrylamide
      Polyacrylate
      Unspecified polymer
 Dispersants
      Sodium silicate
	Polyphosphate
           '
      illillillli,!,!!,1;!!!,|i|illlil,||||||li". ', <;''<||l|:<, 1:1 til' illllllliilLlllillili .lliiJlBHi! 'llllllllllllfliiiilllllllllllinlijlii.iil,lllllllillli i:' iiiiii' i 'I "iiii'Fi it "iiiiiiiiiiiiiiiiiiiiiiii , >, liiiiiiiiuiif.1 '•! ! ,
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  EIA Guidelines for Mining                               Overview of Mining and Beneficiation

  Copper concentrates exiting the flotation circuit contain 60 to 80 percent water.  The concentrate is
  dewatered hi a thickener, then sent to disc or drum filters for final dewatering.  The dewatered copper
  mineral concentrate is then sent to a smelter for processing.  The collected water is usually recycled
  to the milling circuit.  A second product, waste material or tailings, is sent to a tailings pond for
  disposal (possibly after additional flotation steps to recover other metal values).  The settling of solids
  in the thickeners is enhanced by chemical reagents known as flocculants and filter,cake moisture is
  regulated by reagents known as filtering agents. Typical  flocculants and filtering agents used are
  polymers, nonionic surfactants, polyacrylate, and anionic and nonionic polyacrylamides (ASARCO,
  1991).

  Leach Operations

  Copper is increasingly recovered by solution, or hydrometallurgical, methods. These include dump,
  heap, and vat leaching techniques, as well as underground (or in situ) leaching methods.  Each of
  these methods results in a pregnant leach solution (PLS).  Copper is  recovered from the PLS through
.  cementation or, more commonly, by solvent extraction/electrowinning (SX/EW) (U.S. Congress,
  Office of Technology Assessment, 1988).  Currently, solution copper mining techniques account for
  approximately 30 percent of domestic copper production.  Two-thirds of all United States copper
  mines employ various types of solution operations (Weiss, 1985).

  Most ores occur as mineral compounds that are insoluble hi water; leaching involves chemical
  reactions that convert copper into a water-soluble form followed by dissolution. Acid leaching of
 ores'and concentrates is the most common method of hydrometallurgical extraction.  Its use is
 confined to acid-soluble, oxide-type  ores that are not associated with  acid-consuming rock types
 containing high concentrations of calcite (such as limestone and dolomite). Typical acidic leaching
 agents include hydrochloric acid (HCL), sulfuric acid (HjSO^, and iron sulfate (Fe^SO^).  Sulfuric
 and hydrochloric acid leaching at atmospheric pressure is the most common type of copper leaching.
 For certain minerals, alkaline (or basic) leaching and microbial (or bacterial) leaching are effective
 means of extracting copper. The principal reagents used in alkaline leaching are the hydroxides and
 carbonates of sodium and ammonia.  The organism associated with bacterial leaching is Thiobacillus
ferrooxidans.

 Leaching Methods  ffn Situ, Dump, Heap, and Vat)

 Exhibit 3-11 summarizes the major copper leaching methods.  Each of these methods is discussed hi
 the following sections.
                                              3-73                              September 1994

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                                    EIA Guidelines  for Mining
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Ill



Exhibit 3-11. . Characteristics of Copper Leaching Methods
--• "'•''•::^':''f '•;-.].
Ore grade
*»
l^pes of ore .

cure preparation
Container or
pad
Solution
Length of leach.
cycle
Solution ,
application
method
Metal recovery
method
iv^i^ii
Moderate to high
Oxides, silicates,
and* some sulfides
May be crushed to
optimize copper
recovery
Large impervious
vat
Sulfuric. acid for
oxides; acid cure
and acid-ferric cure
jrovide oxidant
needed for mixed
oxide/sulfide ores
Days to months
Spraying, flooding,
and circulation
SX/EW for oxides
and mixed
oxide/sulfide ores;
liuii precipitation
or mixed ores
11^2211^
Moderate to high
Oxides, silicates,
and some sulfides
May be crushed to
optimize copper
recovery
Impervious barrier
•of clay, synthetic
material, or both
Sulfuric acid for
oxides; acid cure
and acid-ferric cure
jrovide oxidant
needed for mixed
oxide/sulfide ores '
Days to months
Spraying or
sprinkling
SX/EW for oxides
and mixed
oxide/sulfide ores;
iron precipitation
or mixed ores
R2£-iSnf^;-
Low
Sulfides, silicates,
and oxides
Blasting
None for existing
dumps; new dumps
intended to be
leached would be
graded, and
covered with an
polyethylene
membrane, or
bedrock, protected
by a layer of select
fiU
Acid ferric-sulfate
solutions with good
air circulation and
bacterial activity
for sulfides
Months to years
Ponding/flooding,
spraying,
sprinkling, and
trickle systems
SX/EW for oxides
and mixed
oxide/sulfide ores;
iron precipitation
or mixed ores
Underground and
/* sitt Leaching
Low to high
(dependent upon
mine conditions
and layout)
Oxides, silicates,
and some
sulfides
None
None
Sulfuric acid,
acid cure, acid-
ferric cure, or
acid ferric-
sulfate,
depending on the
ore type -
Months
Injection holes,
recovery holes,
or sumps '
SX/EW for
oxides and mixed
oxide/sulfide
ores; iron
irecipitation for
mixed ores
Source: Office of Technology Assessment, 1988.




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  EIA Guidelines for Mining	      Overview of Mining and Beneficiation

  In Situ Leaching. The leaching of low-grade copper ore without its removal from the ground is
  known as in situ leaching. In situ leaching allows only limited control of the solution compared to
  other types of leaching (see below).  There are 18 in situ copper operations in the United States that
  leach ore in existing underground mines.

  In situ leaching extracts copper from subsurface ore deposits without excavation.  Typically, the
  interstitial porosity and permeability of the rock are important factors hi the circulation system.  The
  solutions are injected in wells and recovered by a nearby pump/production-well system.  In some
  cases (where the ore body's interstitial porosity is low), the ore may be prepared for leaching (i.e.,
  broken up) by blasting or hydraulic fracturing.  Production wells (and/or sumps in underground
  mines) capture and pump pregnant lixiviant.solution from the formation to the leach plant where
  copper metal is recovered by an SX/EW operation (Biswas and Davenport,  1976;  EPA, 1984a- EPA
  1989).

  Dump Leach Operations. Dump leaching refers to leaching of low-grade sulfide or mixed-grade
 sulfide and oxide rock that takes place on (usually) an unlined surface. Copper dump leaches are
 typically massive, with rock piles ranging hi size from 20 to hundreds of feet in height. These may
 cover hundreds of acres and contain millions of tons of waste rock and low-grade ore (Biswas and
 Davenport, 1976). These operations entail the addition of low pH solution to the piles to accelerate
 leaching, the collection of PLS, and the extraction of copper by SX/EW or cementation.  Since
 widespread application of leaching process is a relatively new process, copper mines have frequently
 applied leaching techniques to recover values from historic waste rock dumps. Collection of PLS
 may not be maximized (i.e., some PLS may escape to the environment).  The sites for these historic
 dump leaches were selected primarily to minimize haulage distances.  New dump leach units are
 typically located and designed to prevent or minnni7f! the loss of leach solution (EPA, 1989).

 The materials placed hi dump leaches vary considerably hi particle size, .from large angular blocks of
 hard rock to highly weathered fine-grained soils. The material is typically less than 0.6 meter in
 diameter. In most dump leach operations, the material is hauled to the top of the dump by trucks.
 The material is deposited by end-dumping hi lifts on top of materials that have already been leached.
 Large dumps are usually raised in lifts of 15 to 30 meters.  After the lift is completed, the top layer is
 scarified (by a bulldozer and a ripper) to facilitate infiltration of the leach solution (EPA, 1989e).

 Natural precipitation, mine water, raffinate (from the  SX/EW plant), makeup water, and/or dilute
 sulfuric acid may be used as leach solution (i.e., lixiviant).  As the lixiviant infiltrates the pile, copper
minerals  are leached by oxidizing the pyrite to form sulfuric acid and ferrous iron solution (the
sulfuric acid solution reacts with the ore minerals to ionize the copper into solution).  Several methods
are used to distribute leach solutions over the dumps,  including natural precipitation, sprinkler
systems that spray the leach solution over the piles, flooding of infiltration ditches or construction of
                                             3-75                             September 1994

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                        of Mining and Benefication	          EIA Guidelines for Mining
                                                          Son of leach solutions	through perforated pipes on top
                                               ), and the injection of leach solutions through drill holes into
             dumps. 'The leach solution percolates through the dump and PLS is collected in ditches or sumps at
             the toe of the dump where the slope of the native terrain provides the means for collection of
             pregnant liquor.  These ditches and sumps are lined at some sites, and are unlfned at others. PLS is
             then treated by solvent extraction or cementation. Metals associated with the copper minerals that are
             also found in PLS include arsenic, cadmium, chromium, and selenium (EPA, 1985; EPA, 1984a).

             Heap.Leaching.  In contrast to dump leaching (described above), heap leaching refers to the leaching
"I"	»'l	"I "III  of Ipw-grade ore that has been deposited on a specially prepared, lined pad constructed using
             synthetic material, asphalt, or compacted clay.  In heap leaching, the ore is frequently beneficiated by
             some type of size TCJu^ff,,1^                   	to	placement	onthe pad (EPA, 1989).
                              •
     Illilfl	iiilHii1 Heapleach pads are constructed above one or more layers of impermeable liner material.  Liners can
            leach sites are selected to take advantage of existing, less permeable surfaces and to utilize the natural
            slope of ridges and ...... valleys for the collection of PLS.  Land jst&ftit.'gpe ...... ofgedqgy 'and .....       .......................... - ......
            however,  is not always within a reasonable hauling distance of the mining operation.
                      basic principles and procedures discussed above with regard to dump leaching operations
            apply to heap leach operations.  Heap leach operations, as opposed to dump leach operations, have
                                                  ]££!£* ...... EPJSS!!!!!0"?, generally are used; (2). leach piles
           may be neutralized after leaching operations are completed;. (3) the leach pad design is substantially
   	:"-d!?!55en£ &e.f the size is smaller, averaging	between 100,000	and	500,000	metric	tons	afore); (4) the
   S8!	""	°"S' *f f061" ^ained (i-e., usually less	than	10	cm);	(5)	the	leaching	is	considerably fester; and (6) the
   ~^~~~	extraction of oxide copjper is greater (EPA, 1989e).    •   '.

           y.at,Leaching. The vat leaching process works on the same principles as the dump and heap leaching
      	i	i	i	||	I,	.-     	=	±	;	-	__---—	----	===~I	-==JMcted	in	a system of
           vats or tanks using concentrated lixiviant solutions. Vat leacbing is typically used to extract copper
           from oxide ores by exposing  crushed ore to concentrated sulfuric acid (lixiviant) in a series of large
        ,,	I'^^i'0*	2S	J1* vats are usually designed hi a series configuration, which acts to concentrate the
        |	cofJpef	coSent	of the sohitions as a function of ore-lixiviant contact time	(EPA, 1989e).  A typical
        |p25-mpter-Iongy 15-meter-wide, and 6-meter-deep vat unit is capable of leaching between 3,000 and
           5,000 tons of ore per cycle.
                i
 i               I
         ,  Vat and agitation (tank) leaching are usually performed on relatively higher grade oxidized ores.
           Tank methods tend to recover copper more rapidly using shorter leach cycle times than heap or dump
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	!	                      ;	;	                                       i	i	                                *;	

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  EIA Guidelines for Mining	•               Overview of Mining and Beneficiation

  leaching operations. Generally, copper recovery is higher, and solution losses are lower with tank
  methods (EPA, 1984).  The.advantages of this method are high copper extraction rates and
  recoveries, short leach cycles, and negligible solution losses (EPA, 1989e).  The disadvantages are
  the low tonnages beneficiated, high suspended solids  concentrations in PLS that a cause problems in a
  SX/EW plant, and high operating costs.

  Copper Recovery from Leach Solutions—Cementation and SX/EW

 Cementation.  In the past, copper produced from leach solutions was typically recovered by
 cementation techniques. In the cementation process, pregnant leach solution (PLS) flows to a
 precipitator pond filled with scrap iron or steel. The  copper chemically reacts with, and precipitates
 onto the steel surfaces.  The iron is dissolved into solution, and the copper precipitates out (i.e.,
 replaces) the iron.  The cemented copper later detaches from the steel surfaces as flakes  or powder
 when it is washed with high-pressure streams of water. Although subsequent treatment by a normal
 smelting/refining method is required, copper recovery from the pregnant solution is very high.

 While cementation has been a source of relatively inexpensive copper, the cement copper produced is
 relatively impure compared to electrowon copper and  must be smelted and refined along with flotation
 concentrates (Beard, 1990).  As a result, it has largely been replaced by SX/EW technology.
 However, several compact and dynamic cementation systems have been developed and are used
 industrially.  The most successful is the Kennecott Cone System Precipitator, by which the PLS is
 forced upwards in a swirling motion through shredded steel scrap. In this system, fine, undissolved
 solid particles (called pulp) are concentrated with the copper cemented particles.  Consequently, the
 cement concentrates containing the pulp must be further beneficiated by flotation. The cemented
 copper is easily floated with xanthate or dixanthogen collectors (Biswas and Davenport, 1976).

 Solvent Extraction.  The first SX/EW plant was developed during the 1960s at the Bluebird property
 near Miami, Arizona. Historically, solvent extraction was largely confined to copper oxides.
 However, recent refinements in leaching methods have, made it economical for recovery from low
 grade sulfide ores. The major advantage of solvent extraction (over cementation) is that the electrolyte
 solution it produces is almost free of impurities.

 Exhibit 3-12 provides a flow diagram for a typical SX/EW plant.  The solvent extraction operation is
 a two-stage method.  In the first stage, low-grade, impure leach solutions containing copper, iron, and
 other base-metal ions are fed to the extraction stage mixer-settler.  In the mixer, the aqueous solution
 is contacted with an active organic extractant (chelating agent) in an organic diluent (usually
 kerosene), forming a copper-organic complex.  The organic phase extractant is formulated to extract
only the desired metal ion (i.e., copper),'while impurities such as iron or molybdenum are left behind
in the aqueous phase. The  barren aqueous solution, called raffinate, is typically recirculated back to
the leaching units.  The loaded organic solution is transferred from the extraction section to the


                                             3-77                              September 1994

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          Overview of Mining and Benefidation
                                 EIA Guidelines for Mining
                                                                                 	I	
    (Hill III 111
                     Exhibit 3-12.  Typical Solvent Extraction/EIectrowinning (SX/EW) Plant
                                         
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.  ETA Guidelines for Mining     	    Overview of Mining and Beneficiation

  stripping section.  The aqueous-organic dispersion is physically separated in a settler stage (Office of
  Technology Assessment, 1988; EPA, 1984; Engineering and Mining Journal, 1990).

  In the second stage, the loaded organic solution is stripped with concentrated sulfuric acid solution
  (spent tankhouse electrolyte) to produce a clean,, high-grade solution of copper for electfowinning.
  The stripping section can have one or more mixer-settler stages.  The loaded-organic phase is mixed
  with the highly acidic electrolyte, which strips the copper ions from the organic phase.  Then, the
  mixture is allowed to separate in settling tanks, where the barren organic solution can be recycled to
 the extraction stage. The copper-enriched,  strong electrolyte flows from the stripping stages to the
 strong-electrolyte tanks, where it is pumped to the electrolyte filters for removal of the entrained
 organics or solids.  The clarified, strong electrolyte flows to electrolyte circulation tanks, where it
 becomes the influent to the electrowinning tankhouse (Office of Technology Assessment, 1988; EPA,
 1984a; Engineering and Mining Journal, 1990).
                                                                                            *
 Electrowinning.  Electrowinning is the method used to recover copper from the electrolyte solution
 produced by solvent extraction. To stabilize the tankhouse operating temperature and preheat the
 incoming electrolyte solution, strong electrolyte (after filtration) is passed through heat exchangers
 where heat is extracted from outgoing, wanner, spent electrolyte.  After passing through starting-
 sheet cells, the strong electrolyte is received in a circulation tank.  In the circulation tank, the strong
 electrolyte is mixed with spent electrolyte returning from the electrowinning cells. The feed
 electrolyte is then pumped to the electrolytic cells continuously.  The electrochemical reaction at the
 lead-based anodes produces oxygen gas.and  sulmric acid by electrolysis.  Copper  is plated on
 cathodes of stainless steel or on thin-copper  starting sheets.  The cathode copper is then shipped to a
rod mill for fabrication. Tie spent acid is recycled and pumped back to the leaching  operation, while
some of the electrolyte is pumped to the solvent extraction strip-mixer-settlers via the electrolyte heat
exchangers (Office of Technology Assessment,  1988; Engineering and Mining Journal, 1990).

Over time, electrolyte hi the electrowinning  cells becomes laden with soluble impurities and copper.
When this occurs, the solution is removed and replaced with pure electrolyte (to maim^n the
efficiency of the solution and prevent coprecipitation of the impurities at the cathode). Purification is
done by electrowinning in liberator cells. Liberator cells are similar to normal electrolytic cells, but
they have lead anodes in place of copper anodes. The electrolyte is cascaded through the liberator
cells, and an electric current is applied.  Copper hi the solution is deposited on copper starting sheets.
As the copper in the solution is depleted, the quality of the copper deposit is degraded.  Liberator
cathodes containing impurities (such as antimony) are often sent to the smelter to be melted and  cast
into anodes. Purified electrolyte is recycled  to the electrolytic cells.
                                             3-79                              September 1994

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                                                                                                 Illllllllllllllllllllllllllll (11111
                              I         I                                  .1
                                                                                       I
        "                                                                            >   I
            Overview of Mining and Beneficiation	            EIA Guidelines for Mining

                                  "                           •                        J
            33.4.4    Wastes and Waste Management
                              1                	 •            '           ,         f	:	:	
                                                      .   • '           "  "  t'' V  '.'        I '  '          ' •  :   .
            Wastes generated by copper mining and beneficiation operations include materials such as waste rock,
            mine water, spent ore, tailings, SX/EW sludges, and spent leaching solution.  Many of these materials
     If IIIIIIJI I] | I'll .       	IIHWIII^IMBIHI	           .                        	I	I	I!!!	I	II	 	I .
            may be disposed of onsite or offsite, and others may be re-used or recycled during die active life of a
     i||||| ^Ufi   .                       •                                                 a	,	
        11111,111111 mine. Waste constituents may include heavy metals, sulfides, or other elements found in the ore, acid
            mine drainage (AMD), and any additives used hi beneficiation operations. (It should be noted that
            the use of the terms "mining waste" and "waste management unit" hi this document does not imply
            that the materials in questions are "solid wastes" within the meaning of the Resource Conservation
        	and Recovery	Act.	As	indicated previously, the term "wastes" includes both RCRA wastes as well as
            other materials.)
::::;::::::	:::::: Mine water     '
           Mine water consists of all water that collects in siirface and underground mine workings as a result of
           imlow^from surface	'ijjrateri	^^p^g^	_.	^^^^	^^	„_.	__	
           pumped out to keep the mine relatively dry and to allow access to the ore body.  At surface copper
           mines, name water may be pumped or allowed to dram to centralized sumps.  At underground mines,
           the quantity of water entering the mine depends on local hydrogeologic conditions. At some
           facilities,, little or no water is .encountered.  At others, groundwater may continually drain into the
           mine; workings.  Underground water inflows are often allowed to dram to low areas of the mine
          ^\|b^:;|mngs	and	gumgs	collect	andjjump the water from the.inine.  At some facilities,, however,' the,
           inflow	of water	is	so	great that the capacities of the underground holding and pump mechanisms are
    JTOiiMrjjjjIjj? jg£ 5^3 Jo" pimp groundwater, leading to a cone 5 depression around the mine and reducing

                                                 RJ&gSfrflfliS	         ,                        .         .    	i;9
           The quantity of mine water generated at mines varies from she to she.  The chemistry of mine water
           Isdependent on the geochemistry of the ore body and the surrounding area. Water exposed to sulfur-
           bearing minerals in an oxidizing environment, such as an open pit or underground workings, may
           become acidified. This potential is greatly dependent on site-specific factors (see Section 4.1).
                             i                                           '                  •
           Pumped water from copper mines may be used hi extraction and beneficiation activities (including
           dust control), pumped to tailings ponds, or discharged.  Because mine water at copper mines is often
           rich m dissolved copper and other metal ions, some operations pump it to an SX/EW plant to recover
           the copper values (Gimming,  1973).
          i     I                                    '                             MI
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          Waste rock is typically hauled from the mine to onsite waste dumps for disposal. At some surface
          mines, these dumps are located within the pits.  Waste rock piles may be highly permeable to both air
               i            i

                                                        3-80                             September 1994

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                            ,  ,                                          	M	!	  '

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  EIA Guidelines for Mining   	           Overview of Mining and Beneficiation

  and water.  Sulfur-bearing minerals in waste rock, such as pyrite and pyrrhotite, can oxidize to form
  sulfuric acid.  Factors that influence acid generation by sulfide wastes include: (1) the amount and
  frequency of precipitation, (2) the design of the disposal unit, and (3) the neutralization potential of
  the rock.  Even where acid-generating conditions are not present, metals found in the waste rock may
  dissolve in infiltration runoff or runon.  This low pH solution can dissolve and mobilize metals in the
  rock matrix and be transported to ground or surface water.  Waste rock disposal units are generally
  constructed without liners. Because even waste rock would contain low concentrations of copper,
  some operations refer to waste rock as. "low-grade ore" or "subore."

 Spent Ore  .      .

 Spent ore from heap and dump leaching  contains residual amounts of lixiviant and associated copper
 and other metal complexes.  The spent ore itself typically contains unleached metals and other
 minerals characteristic of the ore body.  Dump leack piles are reported to range in size from 20 feet
 to hundreds of feet in height and may cover hundreds of acres and contain millions of tons of waste
 rock and low-grade ore.  Most copper leaching operations are not constructed with synthetic liners
 (i.e., they are dump leach units, rather than heap leach units). However, newer units are frequently
 shed where natural low permeability features allow for drainage to a centralized collection point (to
 facilitate recovery of pregnant leach solution).  After collection of leaching solution  no longer
 becomes economically viable, operators must address reclamation/closure of the leach units and
 management of drainage.

 Tailings

 In 1985, 195 million tons of copper and copper-molybdenum ores were treated by flotation
 concentration, resulting in the production of 5.8 million tons of concentrate using 97 million gallons
 of water and 0.32 million tons of reagents. More than 97 percent (189 million tons) of ore tonnage
 processed hi 1985 was typically disposed of as tailings (Bureau of Mines, 1987).

 Tailings impoundments are surface disposal units for tailings generated during flotation.  Slurried
 tailings are transported from the mill to the tailings pond by gravity flow and/or pumping through
 open conduits or pipes. In the arid southwest, where the majority of copper mines are located and
 evaporation rates exceed precipitation, the mine-mill water balance usually requires recycling tailings
 pond water for reuse in the mill.  At copper mines in the  central United States (such as the White
 Pine hi Michigan) the reverse situation exists; precipitation exceeds evaporation rates and tailings
pond water is typically discharged to surface water.  Tailings impoundments may also be used to
disposed of other smaller-volume wastes generated at copper mines including, spent electrolyte
 solution, SX/EW tank sludge, etc.
                                             3-81                               September 1994

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                           ~~ -7—:-;-	:	         •—      -	-f—---	-	-
                       of Mining and Beneficiation	•                          EIA Guidelines for Mining
            Upstream tailings impoundments are most commonly used in the copper mining industry.  In this
            method (as described in Section 3.2), the embankment is erected by depositing successive layers of
            course material on top of the previous dike along the inside of its embankments.  Thus, the centerline
            of the berm progresses upstream toward the center of the Ham  while the outer slope remains stable
            (Bureau of Mines, 1984).
                1            '''',"                   .     '                            •
            Sohkfoa	Bands	g?£.2!l£	E-fS,"-!-	If??.*^,	              	',	
           ;.T .retailing operation ponds can be a source of acid/metal releases by ground and surface water. These
S        include:	pregnant	solution ponds or tanks (where the copper-laden solution is collected), barren   •
            solujios ponds (where lixiviant solution is held before being applied), surge ponds (to manage
•I Illll IIP Illllllll I" III I III IIIIIPl 11 I 111'' III I lllllllllllllllllllllllllii'ilillllllliiiiiin	inn	|ii|i|iiiii	nil	iiiii|	»iii|	1	i	in	11 nil	n	n in i i	11 n	in 11	qiini i	n in nil IIIIIIMI	mill*	j	filii	Si	gnu in	Si	   '  11
            leachate during high precipitation events), make-up water holding ponds, and associated pipes or
                i            i i     i                                               *i I        f
            trendies.  These units may be lined, depending on the quality of the solution to be contained,
            applicable regulatory requirements, the age of the unit, and permeability of the underlying formation.

	,	,	.	PLS and	raffinate ponds generally measure several hectares hi size and, where the topography
	;	',	i	permits, are built into natural drainage	basins.	At	most	older.	copper leaching operations, the
           collection ponds and trenches through which the solutions flow are unlined. In addition, these areas
           .ilillli
           received	little	or	no surface preparation before leaching operations were initiated (EPA,  1989).  At
           newer	leaching operations, 'liners  have been installed in the collection ponds 'to increase solution
    M;	      recovery	and	rnjnmiiTe	environmental	releases.	Generally, the trenches-have been lined  with
    !«^^       total quantity of usable iron ore product snipped from mines in 1991 was estimated to be ,52.8
=	'	•	'	+	million	long	tons	(ft),1	valued ^ $1/7 billion. Of the total 1991 domestic production, 1.97 million It
==•5=!™ of m» product (4 percent) were exported. 'The United States also imported 12.9 million It of usable
	i	Ispja^sg	in,	lgf>l	i|srii,bsnefisiatio.n	and processing. According to the Bureau of Mines, "usable" iron
ZZ^:™".^0??. IP?!*65 mat I*55 tnan 5 percent of the material is made up of manganese (Bureau of Mines,
                                            opeiating     ron ore mines (21 open pt; 1 underground '
           ofieriftioiift, 16 TOnceniration plants, and' 10 pelletizing plants.- The primary iron ore producers are
                  in Minnesota .and, Michigan, ...... wMcji account ...... for ..... about ...... 99 percent of all domestic crude iron

                     tends to measure iron ore production in long tons (It), while the Bureau of Mines used short tons (st) before
                      w*s metrictons (n§).  Production data are presented here in long tons (1 long ton is equivalent to 2,240 Ibs).


                                 IM^	_	,——,—	;™^E5Sanber 1!W4
                                 III llfji; < llili,1 Unilliii !l!ii''I!" niilnili 11	HiUdi1'1! XI'Uill1"!!,: JilBiiJIii,' " *iH .III! ,<|i"! v P'l'ii' niimn1111!!1!,,, lilPIIB" ll n' i'!i I!: '' iPniHji!!; innil!1 ,'''. f -, 'iilV'lK;"' inllliliiiiiill "if 
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  EIA Guidelines for Mining	Overview of Mining and Beneficiation

  edacity mills. Operation capacities tend to be in the range of 1 to 10 million long tons of product
  per year (Itpy). A few mines, however, produce less than 100,000 Itpy (Weiss, 1985).

  Nearly 98 percent of the demand for iron ore comes from the steel manufacturing industry.  Iron is
  also a component in the manufacture of cement and heavy-media materials.  Among the 22 mines
  producing iron ore, most larger operations produce material for the steel manufacturers.  Mines
  producing for cement plants tend to be smaller operations located outside Michigan and Minnesota
  (Bureau of Mines, 1988b,1991a, and 1992).

 3.3.5.1    Geology of Iron Ores

 Iron is an abundant element in the earth's crust averaging from 2 to 3 percent in sedimentary rocks to
 8.5 percent in basalt and gabbro. Because iron is present in many areas, it is of relatively low value
 and thus a deposit must have a high percentage of metal to be considered ore grade. Typically, a
 deposit must contain at least 25 percent iron to be considered economically recoverable.  This
.percentage can be lower, however, if the ore exists in a large deposit and can be concentrated and
 transported inexpensively (Weiss, 1985).   Over 300 minerals contain iron but five are the primary
 sources of iron-ore minerals:  magnetite (FejO^, hematite (FeA), goethite (Fe^^O),  siderite
 (FeCp3),  and pyrite (FeS^.  The first three are of major importance -because of their occurrence in
 large economically minable deposits (U.S. Geological Survey, 1973).

 Iron ore mineral deposits are widely dispersed in the continental United States and form in a wide
 variety of geologic environments, including sedimentary, metamorphic, and igneous rock formations.
 Iron ore deposits hi the United States arc formed by three geologic processes:

      •   Direct sedimentation forming bedded sedimentary deposits
      •   Igneous activity forming segregation or replacement deposits
      •   Enrichment due to surface and near surface weathering (EPA, 1985).

Historically, most iron ore was simply crushed and shipped directly to a blast furnace.  Currently,
some ores are high enough in iron content (greater than 50 percent) to be sent directly to furnaces
without beneficiation activities other than  crushing and washing.  Most ores extracted today, however,
must undergo a number of beneficiation procedures to upgrade the iron content and prepare the
concentrate for the blast furnace. .Technological advancements at blast furnace operations require ore
feed of a specific size, structure, and chemical make-up for optimum efficiency (Weiss, 1985).

3.3.5.2    Mining

Iron ore is mined almost exclusively in surface operations. The most predominant surface mining
methods used to extract iron ore are conventional open-pit and open-cut methods. However, there is
                                             3-83                             September 1994

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            Overview of Mining and Beneficiation
                                                                      EIA Guidelines for Mining
                                                                                       r,
                                                                                      llliHllllillllilll'IS'llllllili:!1!11!!1
 currently one operating underground iron mine, located hi Missouri (five were hi operation in
         i in 1985). The mining of taconite, a tough and abrasive low-grade ore (ranging from 40 to
              .   	i	Si	             i	|	Si	i	i	e	*	-	—	
         int silica and 17 to 30 percent iron) common to Mi
            60 percent;
sota and Michigan, is especially
           difficult because of the extreme hardness of the ore but now dominates U.S. iron production.
               [              ln|i	j,	,	,,,	j	,,;	[(	,_,,	„	;	,	,	,	>	|/	;	;;;	j*;	^	,,;	5,	,	,	,	,	,

           In the iron industry, stripping ratios (overburden/ore) may be as high as 7:1 (for high-grade wash
           ores) or as low as 0.5:1 (for	low-grade	taconite	ores)	(united	States	Steel,	1973).	Wastes generated
           as a result of open-pit and underground iron mining include overburden, waste rock, and mine water
           confining stispended solids and dissolved materials.
         •I11   • ill
           33.5.3    Beneficlation
                    '                                                 ^
           Beneficiation at iron, mines pan include the following:  milling (crushing and grinding); washing; '
   ""	      filtration; sorting; sizing; gravity concentration; magnetic separation; flotation; and agglomeration
           (pelletizing, sintering, briquettmg, or nodulizing)..  The American Iron Ore Association indicates that
           milling and magnetic separation are the most common methods used.  Gravity concentration is seldom
"         .used at existing U.S. facilities. Flotation is primarily used to .upgrade concentrates from magnetic
           separation by reducing the silica content of the concentrate (Ryan, 1991).  Most beneficiation
 	operations will result in the production of three materials:  concentrate; middling or very low-grade
           concentrate, which is either reprocessed (in modern plants) or stockpiled; and tailings.
          "Mflling                	" 	•	"

          Milling operations are designed to produce uniform size particles by crushing, grinding, and wet or
          dry classification. Primary crushing is accomplished by using gyratory and cone crushers (Weiss,
          1985).  Primary crushing yields chunks of ore ranging hi size from 6 to 10 inches.  Secondary
  mm	"" B milling (conminution) farther	J^g^	pUftjcie'	size~	JQ"""^^:	J~	g^	'|	-Jj£jj |j^™	^	rj——
    (11111 ii 11
          Secondary crushing, if necessary and economical, is accomplished by. using standard cone crushers
          followed by short head cone crushers. Gyratory crushers may also be used.
Subsequent fine grinding
                                                                to  e consistency of fine powder (325
                       ...... nss, ....... 0.44 ..... microns). ..............   hough ..... miM taconite ..... operations employ rod and/or ml
                  , a few facilities use autogenous or semi-autogenous grinding systems.  Autogenous grinding
          uses coarse pieces of the ore itself as the grinding media in the mill.  Semi-autogenous operations use
          metallic balls and/or rods to supplement the grinding action of the ore pieces (Weiss, 1985). Between
               grinding unit, hydrocyclones are used to classify coarse and fine particles.  Coarse particles are

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  ElA Guidelines for Mining	        Overview of Mining and Benefication

  Magnetic Separation

  Magnetic separation is most commonly used to separate natural magnetic iron ore (magnetite) from a
  variety of less-magnetic or nonmagnetic material.  Today, magnetic separation techniques are used to
  beneficiate over 90 percent of all domestic iron ore (Ryan, 1991). Magnetic separation may be
  conducted in either a dry or wet environment, although wet systems are more common.  Magnetic
  separation operations can also be categorized as either low or high intensity. Low intensity wet
  processes typically involve conveyors and rotary drum separators using permanent magnets and are
  primarily used on ore particles 3/8 inch in diameter or less.  Low intensity separators use magnetic
  fields between 1,000 and 3,000 gauss. High intensity wet separators produce high magnetic field
  gradients by using a matrix of shaped iron pieces that act as collection sites for paramagnetic
  particles. High intensity separators employ fields as strong as. 20,000 gauss. (Weiss, 1985; United
  States Steel, 1973). Primary wastes from magnetic separation include:  tailings made up of gangue in
  the form of coarse- and fine-grained particles, and wastewater slurry hi the case of wet separation.
  Particulate wastes from dry separation may also be slurried..

 Flotation

 Conventional flotation is primarily used to upgrade concentrates resulting from magnetic separation.
 Over 50 percent of all domestic iron ore is upgraded using this technique. Rotation, when used alone
 as a beneficiation method, accounts for approximately 6 percent of all ore treated (Ryan, 1991).

 Typically, 10 to 14 flotation cells are arranged in a series from roughers to scavengers. Roughers are
 used to make a coarse separation of iron-bearing metallic minerals (values) from the gangue.
 Scavengers recover smaller quantities of remaining values from the pulp.  The pulp moves from the
 rougher cells to the scavengers as values are removed.  Concentrates recovered from the froth in the
 roughing and scavenging cells are sent to cleaning cells to produce the final iron-bearing metallic
 mineral concentrate (Fuerstenau, 1970).  Flotation reagents of three main groups may be used:
 collectors/amines, frothers,  and antifoams.

 Iron-bearing metallic mineral flotation operations are of two main types:  anionic and cationic
 (although anionic flotation is not commonly used in North American operations).  The difference
 between the two methods is related  to which material (values or gangue) is floated and which sinks.
 In anionic flotation, fine-sized crystalline iron oxides, such as hematite or siderite, are floated away
 from siliceous gangue material such as quartz or chert.  In cationic flotation, the silica material  is
 floated and the value-bearing minerals are removed as underflow (Nummela and Iwasaki, 1986).

Wastes from the flotation cell are collected from the tailings overflow weir.  Depending on the grade
of the froth, it is recycled for further recovery of iron units or discharged  as tails. Tailings contain
remaining gangue, unrecovered iron minerals, chemical reagents, and process waste water.
                                            3-85                             September 1994

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                        .  '
                           liillil             	lilt"!
                                                                      is	iin^
                                                                              EIA Guidelines for Mining
ll II	'Ill III
                        'lllll^^
                        , nuiniii I iiiv|i! 11,,!1 •&	.	•	'	ih,	„
        Generally, tailings proceed to a thickener. Thickened tailings may be pumped to an impoundment or
       'p3^ *>* recycled for further beneficlation to collect remaining values.  Clarified water is often reused
       in the milling process.
       Gravity Concentration
       Although gravity concentration was once widely used in the beneficiation of iron ores, today less than
       one percent of total domestic iron ore is beneficiated using this method.  Gravity concentration is used
       to suspend and transport lighter gangue (nonmetallic or nonvaluable rock) away from the heavier
       valuable mineral.  Three gravity separation methods have historically been used for iron ore:
    .	washers, jigs, and heavy-media separators (Weiss, 1985). Wastes from gravity concentration are
       tailings made up of gangue in the form of coarse- and fine-grained particles and process water.  This
       material is pumped	as	a slurry	to a tailings pond.
      Agglomeration
                                              I	iiii'1 'Ilili 'Ili'iFil'' iililllJUK , |l| II
                                                                                    	i	
                         IK inii illillK^               	II	iiiiililliii.!*'lll«^	i	l	i	inn	h	iiiiiini	i	i	iiiiiiiiiiiiniiiiii in	i	in	i	1	i	i	i	
                         activities, agglomeration is used to combine the resulting fine concentrates into
      durable	clusters. The iron concentrate is balled in drums and heated to create a hardened
                    A^omerates	may be in the form of pellets, sinter, briquettes, or nodules.  The
      purpose of agglomerating iron ore is to improve the permeability of blast furnace feed leading to
            Jas-ioIId contact in {he furnace (Weiss, 1985). Pellets currently account for more than 97
              	of all agglomeration products ^erefbre, only the pelletizing technique is discussed below,
              ,,^	olEer	?gg|°mer3tes are pj^^j ^y gj.^^ high-temperature operations).
                         	'	               "      '   ' '     '
                iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii?iiiiiiiiiiiiiiiiiiiiiiiiiiii                                •
                operations produce a "green" (moist and unfired) pellet or ball, which is then hardened
                                                                         ...... eoaoeaMUfSSbS ...... the'"
             ......    .....         .......               .......
      pellets. This is usually accomplished hi a series of balling drums or discs.  Additives such as
      limestone or dolomite may also be added to the concentrate in a process known as "fluxing," prior to
      balling to improve blast furnace recovery.  One of three different systems can then be used to produce
      hardened pellets:                                  '                 '                     •
            l|llllllllllllllllllllllll|l|ll Illllllllllllllllllllll             ^       111 III 111 III  1111 II III  II II 111 I III 111111 111 I 111 111 III III I 111  I lllllllll||ll II 111 111 III I II IIIIIIIIIIIIIIIIIIIIB 11111
            •  Travelling-Grate.  Used to produce pellets from magnetite concentrates obtained from
               tacolite ores. Green pellets are fed to a travelling grate, dried, and preheated.  The pellets
               then proceed to the ignition section of the grate where nearly all the magnetite is oxidized to
               hematite. An updraft of air is then used to cool the pellets.
               Shaft-Furnace. Green pellets are distributed across the top of a furnace by a moving
               conveyor belt and pass vertically down the length of the furnace.  In the furnace, the pellets
               are dried and hejjg|	to	2400°F.	The	bottom	2/3	ofjhg	fjirjasg	|§	used	to	cool	the.pellets
               using an upward-rising air stream.  The pellets are Jj^j^g^J gQm ^je j^gg^ Of me
               system through a chunkbreaker.
            i
  i ill ill in 11	in 111 illllllll il '! ll i* l iii in  ill i ill ill i  llllllll|i  1111!'	i|i|jjiiilii ll | ll iiiill ill illllijil | il 1111 i'|	ill 3-86	

n iii 11 in iiiii i n 11111 ^mii 11 iiiiiii iiiiM     in iiiii^                 	             '
                               , - ,  , :..,	:  ,,;,,;,:   ,,  ',  	.;.••. ,  ,•  	•  s.
                                                                                                  1994

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 EIA Guidelines for Alining	                  Overview of Mining and Beneflciatfon

      •   Grate-Kiln.  Combines the grate technique with a rotary kiln. No fuel material is
          incorporated into or applied to the pellets in this process.  The pellets are dried and
          preheated on a travelling grate before being hardened by high-temperature heating in the
          kiln.  The heated gas discharge from the kiln is recycled for drying and preheating (United
          States Steel,  1973).

Agglomeration generates byproducts in the form of particulates and gases, including compounds such
as carbon dioxide, sulfur compounds, chlorides, and fluorides that are driven off during the
production process. These wastes are usually treated using cyclones, electrostatic precipitators (wet
and dry), and/or scrubbing equipment. These treatment technologies generate either a wet or a dry
effluent, which contains valuable iron units and is commonly recycled back into the operation.

3.3.5.4    Wastes and Waste Management

Overburden, Mine Development Rock, and Ore Piles

.Overburden and mine development rock removed from iron mines are stored or disposed of in
unlined piles onsite.  These piles may also be referred to as "mine rock dumps" or "mine dumps."
As appropriate, topsoil may be segregated from overburden and mine development rock, and stored
for later use in reclamation and revegetation.  These dumps are generally unsaturated and provide a
prime environment for acid generation if sulfide minerals are present.  However, in Minnesota and
Michigan, where most crude iron ore is produced, sulfide-bearing minerals are present in only one
unique geologic environment (Guilbert, 1986).  As a result, acid generation has only been observed at
one site, LTV's Dunka ske at the eastern edge of the Mesabi Range (see below).

Mine Pits and Underground Workings

In addition to wastes generated during active operations, pits and underground workings may be
allowed to fill with water when the mine closes or stops operation, since the need for dewatering is
over. At one site in Minnesota, the Dunka Mine, accumulated water, or mine drainage, has acidified
through contact with sulfide minerals in an oxidizing environment and become contaminated with
heavy metals, as well as suspended solids.  However, the conditions at the Dunka site (as well as two
other abandoned iron mines with similar acid rock drainage) are generally considered unique in the
iron industry (because of localized sources of sulfide ore). Overall, mine water associated with iron
operations is characterized by low pollutant levels.  In fact, the'mine water from at least one mine in
Michigan is used to supplement the local drinking water supply.

At abandoned underground mines, deficiencies in mine shaft protection and mine subsidence may be a
problem.  Although there is only one underground iron mine currently operating in the United States,
abandoned underground iron mines have contributed to the creation of subsidence features.   In West
Iron County, Michigan, subsidence features caused by abandoned Iron mines have grown into large
                                             3_g7                              September 1994

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 •lilllii             •   	iflillljlll'l	lllllll	Il!llllllllii, lll'

            Overview of Mining and Benefication	EIA .Guidelines for Mining

              I1                   • ,                               ''                   |,
            pits and caused interruptions in utility service, damage to roadways, and loss of life (Michigan State,
            Geological Survey Division, 1983).

            Tailings Impoundments
                   H                                     .                  ,       . I    II
            Impoundments,  rather than piles, are used exclusively for tailings management in the iron ore
            industry. As a typical example, the tailings impoundment at LTV Steel Mining Company's facility at
         ,    I                 i	       	•                           I
            Hoyt Lakes is approximately 3,000 acres and contains about 500 million tons of tailings (LTV Steel
   i      i     111  i        ii i       i         	          i        	      ii     i
            Mining Company,' 1991).  Two general classes of impounding structures may be used to construct
            tailings pond at  iron mines:  water-retention dams and raised embankments. As solids settle out in
   ,4          , !'      'I    f     , 'I  , "   •  •            "   ,i in , ', I  '  " 'i.   ,    ,',"'"  I!	 !, , ,    , '" P'
            eimer of these type of impoundments, water is either recycled to the mill or discharged.
                                             		'	!	!'""[	""	;	!'"
            Trace amounts of several toxic metals are found in raw mill tailings effluents.  These metals include
            antimony, arsenic, beryllium, cadmium,  chromium, copper, lead, nickel, selenium, silver, and zinc.
            In some instances (Silver Bay, Minnesota and Groveland Mine, Michigan), amphibole minerals with
	!	"	I	]	'	!"'	!	   .       , 	 i  .'       ' -  ••  i-,  '!"•"    , 't i-,:1 •   j>...       -i,  .       i,..
            fibrous characteristics may be a constituent in the tailings. While amphibole minerals (cummington-
            *  |l i                                                                      |         t
            grunerite) are present in some Eastern Mesabi Range taconite formations, asbestos has not been
            identified as such (EPA, 1976). Most of these contaminants are effectively removed or reduced by
          "         in tailings impoundments.

           33.6    URANIUM
          | Uranium is extracted using ....... surface, underground and solution mining (in situ) techniques.  Although
          "              relativel  young" ...... develc jp ing in the 1940s, the volume of ore recovered by U.S. mines
           has dropped significantly since peaking in the early 1980s. Low commodity prices, a reduced
        „,„ demand ...... from the ...... military and commercial power generators; and abundant foreign supplies are
           responsible for the depressed market.
           33.6.1     Geology of Uranium Ores
           Elemental uranium is generally found in naturally occurring minerals in one of two ionic states: U*+
                      "oxidized" ion) and U4* (the uranous "reduced" ion). * Common uranyl minerals include
                       (CXUO^jVaOg'SHjO), autunite (Ca(UO2)2(PO4)2'8-12H2O), torbemite
                JQz)2(PO4)2-8-12H2O) and uranophane (HaO^CadJO^SiO^-3H2O) (Smith, 1984; Hutchinson
   i~H   and Blackwdl, 1984). Common uranous rninerals include uraninite (UO^), pitchblende (a crystalline
   :^^   variant of uraninite)	and	coffinite	gJSiO*) (Smith," 1984; Hutehinson and' Blackwell, 1984). Uranium
           occurs in the rninerals as one of three isotopes:  U-234, U-235 and the most abundant of the isotopes,
           U-238 (Tatsch, 1976).^ In the uraniuni market, references to OTeL intermediate, and some final
           products, are in terms of percent of uranium oxide or uranium oxide equivalent.  Uranium oxide is a
           generic term for a number of common chemical forms of .uranium, the most common being U3O8.
           YeUpweake is another generic term, used to describe the yellow powder generated as the end product
   i ill (i ii i i iiii iiiii ii I ii11         '     111 iiiiiiii I IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIH ii iiiiiii i	  '   i iii (i i IIIIIIB in ii ill ii i in in i	
                                                                                     »                 h
                                                       3-88                             September 1994
                          iii	

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  EIA Guidelines for Mining              •                 Overview of Mining and BeneSdatioa

  of uranium beneficiation.  The purity of yellowcake typically ranges from 60 to 75 percent U3Og
  (Merritt, 1971).

  3.3.6.2    Mining

  Economically recoverable uranium deposits in the United States historically fit into one of four types
  of deposits: stratabound, solution breccia pipes, vein, and phosphatic. The most economically
  important deposits occur within stratabound deposits within the Wyoming Basin, south Texas, and the
  Colorado Plateau.  Stratabound deposits have been mined using surface and underground techniques
  and are currently the target of solution mining operations. .Grades of ore mined from these deposits
  range from 0.15 to 0.30 percent U3O8.  Solution breccia pipe uranium deposits are located in the
  Northern Arizona Strip and average approximately 0.64 percent U-238; these deposits have been
 mined using surface and underground methods (Pillmore, 1992). Vein deposits have been mined on
 an infrequent basis using underground methods in Colorado and Utah. Phosphatic deposits are
 associated with phosphate ores in Florida; uranium has been recovered to a limited extent as  a
.byproduct of phosphoric acid production from these ores.

 Proprietary information surrounding the small number of mines currently producing uranium limits
 the level of detail available about the nature and size of recent operations.  The primary extraction
 (and beneficiation) method used to recover uranium from ore deposits is in situ leaching.  According
 to the U.S. Energy Information Administration, in situ mining operations generated two-thirds of the
 uranium produced in the United States in 1991.  The remaining 33 percent of the uranium produced
 hi 1991 was by conventional milling operations (DOE/EIA, 1992).  Prior to the drop in uranium
 prices, ore was more commonly beneficiated using conventional milling techniques.

 3.3.6.3     Beneficiation

 In conventional uranium milling, the initial step involves crushing, grinding, and wet and/or dry
 classification of the ore to produce uniformly sized particles.  Ore initially feeds into a series of
 crushers where it is reduced to fragments less than 19mm (3/4 inch). Ore from the crushers  feeds •
 into the grinding circuit where ball and/or rod mills, and/or autogenous or semiautogenous grinding,
 continue to reduce the size of the ore. Water or leach liquor is added to the system in the grinding
 circuit to facilitate the movement of the solids, for dust control, and (if leach liquor is added) to
 initiate leaching (DOI,  1980).

 Classifiers, thickeners, cyclones,  or screens are used to size the finely ground ore, returning coarse
 materials for additional grinding.  The slurry generated in the grinding circuit contains 50 to  65
 percent solids.  Fugitive dust generated during crushing and grinding is usually controlled by water
 sprays or, if collected by air pollution control devices, recirculated into the beneficiation circuit.
 Water is typically recirculated through the milling circuit to reduce consumption (EPA, 1983a).
                                              3.39                              September 1994

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      Overview of Mining and Benefidation
                                                                     EIA Guidelines for Mining
      After grinding, the sluny is pumped to a series of tanks for leaching.  Two types of leaching have
      been employed by uranium mills, acid and alkaline.  Acid leaching has' been the predominant leaching
      process employed by conventional mills, although some mills have used an alkaline system and some
     	lip	Jigii& JK&	(Merritt,	1971). In the discussions;that,follow, an overview, qf leaching is
      provided followed  by a more detailed description of both acid and alkaline leaches.
                                                                                                        -
              steP in any uranium leaching operation is oxidation of the uranium constituents.  Uranium is
     found as uranium dioxide (UO2, U*4 oxidation state) in many deposits (pitchblende and uraninite).
     Uranium dioxide is insoluble;,,,, to create'a soluble form, UOj is oxidized from the IT" to .the, U*6
     oxidation state.	Iron jnratjriftin.	the	ore,	and	oxygen, are- used to perform' oxidation via the
     following reactions (Twidwell et al., 1983):                                .
          (1) alkaline  tlCfe + teC^ ?± UQ,
          (2) acid~	"Uft	+	2Fe-:5	£'	UO??	
    Iron can be readily regxidized by the addition of O2, sodium chlorate (NadO3), or manganese oxide
 illiiill (jf^nOj) to the lixiviant.
  	!J* ff£™	2ft	2	J,2£fiS i8 me stabilization of the uraniferous ions in solution. The,,, uraniferous
    ions form stable, soluble complexes with sulfate (SO,*) prcarbonate (Cp^2).  Sulfuric acid is added
    as the source for sulfate ions; sodium bicarbonate, sodium carbonate, or carbon dioxide are added to
    alkaljne leach circuits to provide a carbonate source.  Uraniferous complexes are formed through the
    *-"      reactions (Twidwell et al., 1983):
                      ffia	+	2i!	          	2	HCMCO^	t
                            -J- 6SO/2 5* UO2(SO4)6'4.
             *l^ leaching operation, sulfaric acid is added to the crushed ore slurry to maintain the
              10.5 and 2.0. Twenty to 60 kilograms of sulfuric acid per metric ton of ore are normally
	jNaClOi	SLMnOj	!?	.added	to	rnajntam.....the	oxidation	by iron.'
	i	SSSSIS	ISSS	!§	ISsiiily found in uranium deposits,	the	ore	body	itself suppUes the iron in the leach

i	step
                    i:, ...... fli ...... Hi; ...... liila).

                                                                                            lill 'iillllll1 ' i (III
 ^^aljae leaching is not as effective as acid leaching for uranium recovery and is not "used except in
   caSK of hi£h Kme^ntent ores.  Typically, ore bodies containing greater than 12 percent carbonates
             *^ Ie??h«i- MtetiB* leaching is primarily employed in fn situ mining operations,
           a fcw conventional mills have maintamed alkaluie leach circuits (Merritt, 1971).  Alkalme
                      	SilSuSSSPS oxidant ^ long retention times to oxidize the uraniferous
                     * **" 198-3>- A8 stated Previously, oxygen and a carbonate source are added to
                             111 iiiiiiini inn	iii i nil 111 iii	iii   .  ii 11! iiiHiii niiii i in 11 in iiiiii (i  in iiiniii 111 linn in i ivi i IN iiiinii
                                              3-90
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EIA Guidelines for Mining _ Overview of Mining and Benefication

water to make up the lixiviant.  The carbonate (CCV2) and bicarbonate (HCO3") concentrations are
typically 40-50 g/L and 10-20 g/L respectively (Merritt, 1971).  For its leaching process, the
Highland in situ project injects O2(g) and CO2(g) hito the lixiviant prior to underground injection.
The dissolution of CQj in the lixiviant produces both CO3'2 and HCCy ions (Hunter, 1991).

Leaching maybe performed hi tanks, heaps or in situ.  In situ leaching is practiced on low-grade
ores; after crushing and grinding, higher grade ores are typically leached in tanks at conventional
mills.  Low-grade ores may also be amenable to heap leaching; however, the available literature
indicates that the application of this technique to uranium ores has been and is limited and
consequently it is not be discussed hi detail. Leach tunes vary depending on the grade of the ore,
grain size (amount of grinding), and the method used.  Leaching in tanks may take from four to 24  .
hours while heap leaching may be measured in days or weeks (Twidwell et al., 1983).  ..

Once the uraniferous compounds have been leached from the ore, the pregnant leach solution is
separated from the solids using classifiers, hydrocyclones, and thickeners. Sand-sized particles are
removed first and washed with clean water or barren lixiviant/raffinate .  Continued treatment
removes the slimes, which are also washed. Depending on the settling time allowed by  beneficiation
operations, flocculants may be added to the process to encourage settling of suspended solids. After
final washing, the solids (sands and slimes) are pumped as a slurry to a tailings pond for further
settling. The pregnant leach solution then enters a solvent extraction or ion exchange circuit. Wash
solution is recycled to reduce consumption of leach chemicals, solute, and water (DOI, 1980; EPA,
1983a).                 .        .

Solvent extraction is an operation that concentrates specific ions. Generally,  solvent extraction uses
the immiscible properties of two solvents (the pregnant leach solution and a solvent extraction
solution) and the solubility properties of a solute (uraniferous  ions) hi the two solvents.  Solvent
extraction is typically employed by conventional milling operations since solvent extraction can be
used in the presence of fine solids.  The pregnant leach solution is mixed hi tanks with the solvent
exchange solution.  Selection of a solvent in which the target solute (uraniferous ions) is preferentially
soluble allows the solute to migrate to the solvent exchange solution from the pregnant leach solution
while other dissolved compounds remain hi the leach solution. Normally, the solvents are organic
compounds mat can combine with either solute cations or solute amons.  A» wanyl-caxbonatec or
sulfates are commonly generated in ti» leaching step, anionic soiveni extraction solutions are typically
employed;  cationic solvent extraction solutions way be employed depending on liakjae characteristics
of die «es or Jeadnng
Among the anionic SX solutions are secondary amines with aliphatic side chains, high molecular
weight tri-alkyl tertiary amines, and quaternary ammonium compounds.  Cationic SX solutions
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                                                                                                    	II	
            Overview of Mining and Benefication
                                                                EIA Guidelines for Mining

            include monodocjecyl phosphoric acid (DDPA), di-2-ethylhexyl phosphoric acid (EHPA), heptadecyl
            phosphoric acid (HDPA), and dialkyl pyrophosphoric acid (OPPA).  (Twidwell et al., 1983)

                    * the solvent-exttaction solution is diluted in a low cost carrier -such as kerosene with, a
           tribal phosphate modifier or a long chain alcohol (Twidwell et al., 1983).  The uraniferous ions
           preferentially move from the aqueous pregnant leach solution into the organic solvent as the two are
                    d fl?ated *D°I> 198°^' After'the uraniferous compounds are thus' enacted from the '
                    I«cE ...... solution, the barren lixiviant         .....  "'"  ^'       .......
                                                                                             crcut.

           After the solute exchange has taken place, the pregnant solvent extraction liquor must be stripped.
           rocess ;(Twidwell et al., 1983).        .                                    ;

          lake solvent exchange, ion exchange operations make use of organic compounds to perform solute
          C0ncenteation- Generally, fixed organic resins contained within a column are used to remove
          uraniferous c?)inpound| £"*!§e, E^BMnt leach solution by adsorption.  After adsorption, the
          UtaiferoUS COn9>0m^ rcsins are released (eluded) by a stripping solution and sent to
                 within meir operations.
         Resins are constructed with anionic or cationic functional groups (typically anionic for uranium
         'con^
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 EIA Guidelines for Mining                         .       Overview of Mining and Beneficiatfon

 exchange column increases.  Once the uranyl ions at the outlet reach a predetermined concentration,
 the column is considered to be loaded and ready for elution.  Typically, the pregnant leach stream is
 then directed to a fresh vessel of solvent exchange resins.  A concentrated chloride salt solution is
 then directed through the loaded resins, eluting off the uraniferous complexes. The pregnant elute'
 liquor can then be directed to the precipitation circuit.  The pregnant elute solution may be acidified
 slightly to prevent the premature precipitation of uraniferous compounds (Twidwell et al.,  1983).

 Once the uraniferous ions have been concentrated by solvent extraction or ion exchange, they are
 precipitated out of solution to produce yellowcake.  The precipitate is then washed, filtered, dried and
 drummed. The chloride stripping solution is recycled back to the stripping circuit. The type of ion
 concentration solution (e.g., acid or alkaline solution) governs the precipitation method  employed.
 With acid pregnant stripping liquors or pregnant elute liquors, neutralization to a pH of 6.5 to 8 using
 ammonia hydroxide, sodium hydroxide or lime results  in the precipitation of ammonium or sodium
 dhiranate (Merritt, 1971).  Hydrogen peroxide may also be added to an acid pregnant stripping liquor
 or pregnant elute liquor to precipitate uranium peroxide (Yan, 1990). All forms .of the uraniferous
 precipitate are known as yellowcake.

 Alkaline pregnant stripping liquors or pregnant elute liquors typically contain uranyl carbonates.
 Prior to precipitation of the uranyl ions, the carbonate ions must be destroyed.  An acid (usually
 hydrochloric acid) is added to the carbonate concentrate solution to break down the carbonates to
 carbon dioxide; the carbon dioxide is vented off.  Once the carbonates have been destroyed, the
 acidified solution is neutralized with an alkali or treated with hydrogen peroxide to precipitate the
 uraniferous compounds.  Precipitation operations based on neutralization of acid solutions are favored.
 because of the higher purity of the yellowcake product; sodium, carbonate, and, in some cases,
 vanadium, are impurities that may be present hi yellowcake produced from alkaline neutralization
 (Merritt, 1971).

The yellowcake is separated from the precipitation solution by filtration.  Thickeners may be used in
 conjunction with filtration units. The filtered yellowcake can then be dried and packaged for
shipping (Bureau of Mines, 1978). The supernatant generated from precipitation and dewatering
 circuits can be recycled to the respective solvent extraction or ion exchange  stripping solution.

Typically, yellowcake is shipped to a Federal facility for processing.  In the processing step, uranium
fluoride (UFj) is produced from yellowcake.  The uranium fluoride is then enriched, an operation that
concentrates the U-235 from 0.7 percent to approximately two to three percent.  The enriched
uranium fluoride is further refined to ultimately produce the fuel rods used in nuclear reactors.

In situ leaching is the most commonly employed solution technique and continues to be employed by
at least two mines in Wyoming.  Nebraska's Department of Environmental Control permitted an in
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	Overview of Mining and Beneficiation
                                                                                  EIA Guidelines for Mining
	|	
    B,	tii	2S
             amoebic
    ilW^	•	.-
	  mineral d
                       ton in 1990 although its operational status was not determined (NDEC, 1990). Deposits
                      to in situ
are usually (if not always) within an aquifer.  Water quality within a
                          LI
                                                                                                                  '
                                                                                           	              '
                    deposit may vary depending on the presence of and boundary between oxidizing and reducing
             groundwaters. Ore body characteristics, including chemical constituents, grade, and permeability, are
             key considerations in the development of production methods (selection of lixiviants, arrangement of
             well patterns, etc.). Ideally, the deposit should be confined by impermeable strata above and below
          .   the deposit to prevent contamination of adjacent aquifers by excursions (solution leaks from the ore
             zone).  In situ production operations consist of three phases:  removal of minerals from the deposit,
             concentration of uraniferous minerals, and generation of yellowcake.  In addition to  the production
	,	  operations," water treatment	and,	in some	cases,	deep	well injection facilities, are employed.

             In the case of in situ operations, beneficiation serves as the first phase of the mining operation. In in
            situ mining, barren solvent (lixiviant) is introduced to the deposit through injection wells to initiate
m   i   ,      the operation. The lixiviant contains both an oxidizing agent to solublize the target minerals  and a
                i                                      <                                   iii
            complexing agent that binds to the target minerals and keeps them in solution.  Wyoming in situ
     	llJiiiin  "in	••iiiil	"	if	"	3	!	!	15	9	3	5!	!P	'-!S	
•••I     .  operations recover uraniferous compounds using oxygen gas as the oxidizer and carbon dioxide, as
            the complexing agent (WDEQ, 1991). The barren lixiviant is charged with carbon dioxide as the
IH^  IIH^    lfl|M    • •^•••••1 lilllllH IIIIIIIIB lllllllllllH IIIIIIHI Illllillllllllllll 111 I 111 II 111 II •• llllllnl IIIIIIIH^^^  Illllllllllllll 1 tin iillllll Illllliilllll1 •	
        ,^   solution	leaves the	ion exchange facility. Oxygen is injected into the solution in the  wellfields,
            immediately before'the lixiviant flows into the injection wells.  As the solution moves through the
            deposit, uraniferous minerals are oxidized and uraniferous ions  move into solution.  Carbon dioxide
              * i                 '                                          i      .        i1     '    ••        -
            m the lixiviant reacts with water, forming carbonic acid, which in turn complexes with the solubilized
            uraniferous ions, forming uranyl carbonates. The uranyl carbonates and gangue minerals solubilized
            in the operation remain in solution as the pregnant solution is pumped to the surface through
	i	production (recovery) wells.                        "
                                                                                                       mi in 11 niiiiiiiiiiiiiiiiiiiiii iii
       	II	llllllli Bill
                  ••Illllfl 11 ll'l Hill,11"!
                                 Ill	ITInll' 111	IIIIIH       	I	Ill	II11	1, II	Ill	ni I	I	Inn i, I'll	i, iillllll	HII lllillilirili
                                                                                           ,11 Iillllll 111 ill1 lull	Ill)' l'
                                                                                                             nil	,
                                                                                                                   	iii	i
                    : lixiviant is pumped from die production wellheads through sand filters to remove any large
                I ,.  , i      ,   •    '     «                                   ,    „ '•'   I.,1'" ;	   , |.                 i
            pardculates; the lixiviant is then transferred to ion exchange units. Depending on die facility, the ion
            exchange units may be placed in trailer-mounted tanks or moved via tanker truck from satellite plants
            to a central processing facility.  When the resins hi die ion exchange units are loaded, the uraniferous
            compounds are stripped from the resins and precipitated to form yellowcake. The lixiviant,  after
            passing through the ion exchange unite is recharged	with	carbon	dioxide	and oxygen following the ion
            exchange circuit and injected back	'into	me" ore'body!	"	
   ,,        Numerous well patterns have been investigated since the early	1960s \vbsninsitu "mining	techniques '
 	were first employed. Five spot	well	plrtelms', 'which	consist'	of	four'	U^eietiTn wdk fonni^;	the	'	

 	"»	''"'"'	'	'injection and production" wells are used in narrow deposits.	The" spacing between mjection and	'""'""'
 ISIISI	ii.:::: production wells can range ^m^j^^^^^Jtezn^«|df^^	2§!!5!!!?	M^^iriMI'''!?!?^	
           • also .vary.                   '	'	'	'	'	'	'	'	i	i	'	'	'	MI	'	"	i	i	'	MI	^	'	'	'	"	" ^
                                                	3-94
                                                Illi1' iii'liiS'i1 IE'l!!W,,, i' lli'ii I!1" :!'i!!:!!'jiiSI'-IRlllilHl i11*!11!1 "OlWlilllfiiil'iiWilli^iiiii!; i 'I11'!'
                                                                                             September 1994
           	iii

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 EIA Guidelines-for Mining                               Overview of Mining and Beneficiation

 Mining units are portions of the deposit to be mined during one. operation, often, following "pods" of
 ore deposited along a roll front. Mining units may be mined in sequence or simultaneously.
 Pumping rates at one in situ operation in Wyoming ranged from two gallons per minute (gpm) to 30
 gpm for injection wells and five gpm to 40 gpm for production wells. Approximately one percent of
 the fluid drawn from the well field is removed as a bleed to generate a cone of depression within the
 "production zone." Pumping rates can be varied at each well individually in order to compensate for
 differences in permeability of the deposit and the gradient being generated by the production
 operation.     .        .'      ' .              ~

 Uranium recovery rates at in situ operations are highest within the first year of operation;
 economically viable recovery within a wellfield usually lasts one to three years under recent (1990s)
 market conditions.

 Restoration of the aquifer can be conducted using one (or more) of the following techniques:
 groundwater sweep, forward recirculation, reverse recirculation, and directional groundwater
 sweeping. In some cases, a reducmg agent may be injected prior to any  restoration to reverse the
 oxidizing environment created by the mining process.  A reducing agent  may also be injected during
 later stages of restoration if difficulties arise in stabilizing the.-aquifer (Lucht, 1990).

 A groundwater sweep involves the selective operation of production wells to induce the flow of
 uncontaminated groundwater into the mined zone while "the withdrawn water continues to be treated
 through the ion exchange circuit. Contaminate water withdrawn from the aquifer can be disposed c t
 in lined evaporation ponds or treated and discharged.  Groundwater sweeps are most effective in
 aquifers with "leaky" confining layers, since  uncontaminated groundwater can be induced to flow in::
the mined areas. Typically, two or more pore volumes are required to improve water quality
parameters.  The disadvantage to groundwater sweeping is its  consumptive use. of groundwater
 (Osiensky and Williams, 1990).     .                  .

Forward recirculation involves the withdrawal and reinjection  of groundwater through the same
injection and production wells that were used during the mining operation. Groundwater withdrawn
from the mined aquifer is treated using ion exchange or reverse osmosis with the clean water being
reinjected and recirculated through the system. The water being reinjected is treated to the extent that
 it meets or exceeds the water quality required at the endpoint of restoration. The method does not
allow the removal of any lixiviant or mobilized ions that may have escaped from the mined aquifer.
For this reason, forward recirculation is most effective in restoring the portions of the aquifer
associated with the ulterior of the well field (Osiensky and Williams, 1990).

Reverse circulation techniques can also be employed hi which  the function of production and recovery
wells is reversed.  Again, "clean" water is injected, this time through the recovery wells, while the
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liiiiiiiiilliiiii iiiiiii iiiiiiinii                                 11 nil inn in iiiinnn i in n n i in in nliinin i linn i inn in in 11 linn in 11 ill 11 linn 11 iniiiiiinn 11111 iiiiiii in 11«in inn««i iiiiiii i linn i ill iiiiiiiil^
iiiiniiiiiiini iiiiiiiiniiiiinni n in  iiiiiiiiiiniiiiiiiiiiiininii^^^^^^     inn HIM iiiinliiiiiiiiiiiiin||iiiiniiiiiniiiiniiiiiiinniiiinninni iniiiiiiiiiiiniiiinnni in n inn in in in niiiiiiiiiniiini in  i n  in in nil i inn  iiiinnn i iiniini iiiiiiiinin niiiiiiiiiiiiiiiiini n n nil in inn inn in in inn nil iiniiiini iiinihiiiiiiiniiiiiiniiini n iiliiinniliniiniliininiiiiiinii
                iniiiiliiiiiinii iiiiiiliiiinniii||iiiiiniinniiniiinn
             Overview of Mining and Benefication
                                                                                                             	11
                                                                                                             in in  in in n In n I
                                                                         EIA Guidelines for Mining
             injection wells are employed to'withdraw groundwater from the aquifer.  This method is also more
             effective in restoring the aquifer in the interior of the well field than along the perimeter (Osiensky
             and'Williams, 1^90).                                           '            	'	"	:	"	'	
    11 iiiiiii in i
    111 IB
  Directional groundwater sweeping techniques involve the pumping of contaminated groundwater from
  specific wells while treated water (at or surpassing baseline quality) is injected into the aquifer beyond
  the mined sections of the aquifer.  The clean water is then drawn into the contaminated portions of
  the aquifer, removing the residual mobilized ions. Clean water injection can progress across a
  lllllllllllll  j   i    n    in ill   mi nil  i j  n nn i  i n inn in ninnim nun j  li  111 11 i in f  1111 in iiini in  n  mini in inn in in inn I"1   i ii.!p!iiiiiiiniiigifi!ii!iiiiiii!iiiiiiiniiiiijnniiiii!iiiiiiiiiiilil           	iiiiiiiniiiiiiiiiiiiiiiiiiiiiiiiiirj'/iHiiiiiii	.'iiiiiiiNnjiiiiiii.'iiinivnr,
  wellfield as the contaminants are progressively withdrawn (Osiensky and Williams, 1990).
            Uranium can be recovered during the early stages of the restoration process as the water from the
            production wells passes through the ion exchange system!.  Eventually, uranium recovery is abandoned
                f                   „             '                                           [    	I,	;-i	
            while restoration continues.  A rinse of multiple aquifer pore volumes is typically required to reach a
            satisfactory level of restoration.  The number of pore volumes required depends on the ease with
            which the aquifer returns to baseline conditions and the permit requirements established in State
         :	'	Wlllams, 1990; Bureau of Mines, 1979).
           Demonstration of successful aquifer restoration is accomplished through extended monitoring.  The
           State of Wyoming, for example, requires that selected wells be monitored for stability for a period of
           at least six months following the return of monitoring parameters to baseline levels (WDEQ, 1990)..
                                                   •           '
             rastes generated by uranium mines and nulls would include those generated in other mining sectors
                 	waste	rocl,	sp'extractibnTieacning	
                                                                                                                          ~	ill
                                                     tailings, and refuse).  Mining method
 (conventionalversus solution) has a bearing on the types of wastes produced.  Under the Uranium
 Mill Tailings Remediation Control Act (UMTRCA), source handling licenses issued by the Nuclear
 Regulatory Commission (NRQ place specific requirements on the disposal of radioactive wastes; the
 design and construction of tailings impoundments thus have to address requirements for permanent
 storage of these wastes.	Radionuclide-containing wastes generated by in situ operations-are typically
	shipped'11 to tailings	impoundments	at	mill sites.
               greatest volume of waste generated by ogen git and underground mines is waste rock, which is
                                                    §om£	HE!£	5** raay *** ^^d  °'r onsite 'construction
                                                                                                                 	iiiiiiiiiiiiiiiii 11	i	i	nil
           (roads, foundations, etc.). The generation of acid mine drainage is one of the principal concerns
           siirrcfilling waste rock hi other mineral sectors.  The potential for generation of acid drainage from
                          rock has not been addressed in available reference materials.  However, pyrite is
                                                       ores, and may present the potential to create acid mine
           drainage. Other materials generated by open pit and underground mining operations, including low-
                : ore and mine water, are ^y^gjjy wai]ZS^ pireite during the active life of the facility.  Low-
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' EIA Guidelines for Mining   	     Overview of Mining and Benefication

  grade ores that are not beneficiated ultimately become waste rock. If a mill is co-located with a
  mine, mine water can be used as makeup water in the beneficiation operation. If a mill is not nearby,
  mine water may be treated and discharged as mine drainage or used for dust suppression.

  The principal waste generated by conventional beneficiation operations is tailings. In situ operations,
  and to a lesser extent conventional mills, generate waste leaching.solutions. Disposal of these wastes
  is dependent on the type of operation; beneficiation wastes generated by in situ operations are
  disposed of by one of four management methods: evaporation ponds, land application, deep well
  disposal, or shipment to NRC-licensed waste disposal facilities. Most beneficiation wastes generated
  at conventional mills are disposed of in tailings impoundments.

  Waste constituents of concern include: radionuclides (radium, radon, thorium, and to a lesser extent
  lead), arsenic, copper, selenium, vanadium, molybdenum, other heavy metals, and dissolved solids.
  Brines, spent ion exchange resins, and chemicals used in beneficiation operations are also constituents
  of wastes generated during beneficiation. Airborne particulates from blasting, loading, and vehicular
  traffic can also be of concern.

 3.3.7    OTHER METALS

 3.3.7.1     Aluminum
                                                        f
 Bauxite (a mixture of primarily three aluminum hydroxide minerals, diaspore,  gibbsite and boehmite,
 and impurities) is the  ore of aluminum (Hurlbut and Klein, 1977). Deposits of bauxite in the United
 States are located in Arkansas, Georgia and Alabama.  In 1992, bauxite was being mined from
 surface excavations in Georgia and Alabama (Bureau of Mines, 1993).  Virtually all of this domestic
 bauxite ore is consumed in the production of nonmetallurgical products (primarily refractory grogs)
 and not in producing aluminum (Bureau of Mines, 1993). Imported metallurgical-grade bauxite 'is
 used in the production of aluminum in the United States.'

 Alumina production is shining to the large-scale bauxite producing countries in response to increasing
 energy costs in North  America and Europe (Bureau of Mines, 1993).  If this results hi increased costs
 for alumina for U.S. plants, nonbauxitic aluminum resources in the United States may become
 economically more attractive.  Current conditions indicate that the United States will continue to be a
 major importer of metallurgical-grade bauxite and alumina, precluding the  need for extensive
 expansions of U.S. bauxite mines (Bureau of Mines,  1993).

 The two active bauxite mines use the general surface mining operations discussed in Section 3.1.
 Draglines, shovels and haulers remove ore from open pits and transport it to a  storage area.  Ore may
 be loaded directly from storage to the processing plant, or it may undergo beneficiation at the mine.
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           Overview of Mining and Benefication
                                                                     EIA Guidelines for Mining
   . 	IIIIIN iillillll ih I	I11!1
•iiiiiiiiiiiiiiiiii i ii in	
           Beneficiation
                                                                             P ''    j1,,.'       •       , „
                                                                                     |S^^
                                                             Crushing	is common	to	all bauxite	
           processing; however, the steps following crushing depend on the makeup of the ore.  After crushing,
           the ore may be washed to remove sand'"and clay sized impurities.'  Impurities such as iron, and ,
           titanium may be removed using heavy media or magnetic separation, jigging, or spiral concentrators.
           The washed ore is generally shipped without further processing; however, it may be dried or calcined
           at the	mine. Most bauxite ores are not dried at the mine site, because drying	may	create	serious dust	
               r
           problems during transportation and handling (EPA, 1979).
                                                                                                                   ;::i	iiij iii! iiiiii
The- wastes produced ...... from the beneficiation ..... of bauxite ores is the wastewater used in the' washing *
process. Generally this water is discharged to the pits and not to surface waters.  Chromium, copper,
        * ........ nickd ..... a^'zliichave ..... ^j| ..... ^j ..... ,-—— ...... ^ ..... — - ..... _ _ ___ ....... g. ..... _=___ .......  _ ......  __ ...... ___ .....................
                         He ..... drainage ...... can be ...... 'fflmfpSL' (&&&&)'.
                 1982)1 ....... In
           3.3.7.2     Tungste

The princijpal ore minerals for tungsten are wulframite ((Fe,
                                                                             and scheelite
                                                                                 ,                "
           resistance and good thermal and electrical conductivity, make it an important material for ..... 'use ....... in"
                                         Tungstenoreshavegenerally
                                            .using gravity concentration or
	"	gravity	of tungsten minerals is high and therefore gravity concentration methods primarily are used.
          However, scheelite (the principal U.S. ore) is very friable and in the process of wet-grinding a
	'	(mBiderab'ie	amount'	ot^slxmes1	axe produced'and	•—.——-«	.^H*—	—	«,-.-».	.—«g««	9j"Q	•	
               I         i               •                       , i     HI   i               ir
          increase overall recovery, finely divided scheelite particles in the slimes are concentrated by flotation
          techniques using fatty acids as collectors.  Several hydrometallurgical procedures are used for
          upgrading tungsten concentrates.  Scheelite concentrates from flotation tend to be lower grade than
          gravity concentrates.  Calcite and apatite are the principal contaminants hi these low-grade
          concentrates (scheelite concentrates seldom contain sulfides in large amounts).  These impurities may
          be leached out
                      , and the concentrates upgraded in die process. A first-stage leach with
          hydrochloric acid (HC1) removes the calcite as calcium chloride (CaClj) solution, which is discarded,
                          	"'"	'	!	!!!|"|	"	'	I	'	I!!""!	:l	;'' r1 *  ' '   '  F "
          while a second-stage leach is used to dissolve the apatite, which is not dissolved hi the presence of
          calcium chloride,

          One of1 the many	variations of'tungsten	ore"'benefication 'pyoggjj^g^1	jj!m^	h^dromeailurgicai	
                                           i     i  i i                          i          i           i
          treatment of low-grade scheelite group concentrates to produce calcium tungstate. A water slurry of
          scheelite concentrates from flotation machines is digested in a pressurized digester vessel with sodium
          carbonate and steam to produce tungstate and molybdate in solution.  To remove the_ molybdenum,
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       Guidelines for Mining	    '         Overview of Mining and Benefidation
                                                                          .'
  the solution is filtered and heated to 91 °C (195 °F), and sodium sulfide is added to precipitate
  molybdenum. The solution is adjusted to pH 3.0 with H2SO4 to complete this separation.  The hot
  purified solution is neutralized with sodium hydroxide to a pH 9.2, then treated with calcium chloride
  to precipitate calcium tungstate.  Alternatively, the filtered solution after molybdenum separation may
•  be solvent-extracted by a proprietary process to produce ammonium paratungstate, which is
  crystallized out of solution and dried (EPA, 1976).

  The discharge from tungsten milling operations has been found to contain high concentrations of
  copper, lead, and zinc (EPA, 1982).

 33.73    Molybdenum

 Molybdenum is an important metal for use as an alloying agent in steel, iron and superalloys (Bureau
 of Mines, 1993). Molybdenite, is the major ore mineral mined for molybdenum. In the United
 States, the economically important deposits of molybdenite are generally low-grade porphyry or
.disseminated deposits, but contact-metamorphic zones, quartz veins, pegmatites and aplite'dikes, and
 bedded deposits in sedimentary rocks have also been exploited for molybdenite.  Most porphyry
 copper deposits contain low concentrations of molybdenite (0.02 percent to 0.08 percent). Primary
 molybdenite deposits typically grade 0.2 percent to 0.5 percent molybdenite. In 1992, 45,500 metric
 tons of molybdenum was mined in the United States, two-thirds for export.  Three mines (in
 Colorado and Idaho) mined molybdenum ore and 11 (in Arizona, California, Montana, New Mexico,
 and Utah).recovered molybdenum as a byproduct. The United States was the major producer of
 molybdenum in 1992, and will continue as a top five world producer throughout the rest of the
 century (Bureau of Mines, 1993).

 Molybdenum ore is mined by both open pit and underground operations in the United States.  In
 1992,  approximately 40 percent of U.S.  production was from underground mines and 60 percent fro-
 open pits.  Underground mines typically use caving methods, since these methods allow for the
 economic removal of large tonnages of low grade ores at a low cost. Conventional  open pit mining
methods are used. In underground mines, very little waste rock is removed.  Significant tonnages of
waste rock can be removed in the development and mining of an open pit.

After the molybdenum ore is  mined, it is transported to a mill for beneficiation.  The ore is generally
crushed and ground at the mill before traditional flotation methods are used to concentrate the ore
minerals. A final concentrate of 90 percent to 95 percent molybdenite is produced by the
beneficiation operation. The major impurities in the concentrate are copper, iron and lead minerals.
Molybdenite recovery from copper ore is more complex due to the low percentage present hi the ore.

As hi the flotation of other ores, the major wastes produced are tailings, and these are generally
disposed of in tailings impoundments.
                                             3-99                              September 1994

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              Orerview of Mining and Benefication	J2IA Guidelines for Mining
              3.3.7.4    Vanadium
SSSlfJ ..... !! ..... i11!!!!!! !'!,  &nadimp, ....... is generally not mined as the primary metal of an ore, but as, a co-product, as in carnotite
             ores (recovered for uranium and vanadium) mined in the western United States. Currently, one mine
             in fhe United States recovers vanadium as the primary constituent of the ore.  The primary use of
             vanadium is as an iron and steel alloying agent. Mining of the uranium and vanadium ores in the
                Jl              m               ,      .......... ',";,,!, ,„,;„,, ........ • , ........ ,,;, ,„, ..... ,,,  „,,,,„, ...... „  ,,,,;,„'; "„; ........ ;,„,,,, •„, ....... i „';•:!! ,:,!,, ,,„,,,, .;i",f.1;ljl;ll,i .......... :,,, ......... „„, ....... ........ / ,, ....... „
             western United States has employed open pit and underground mining methods. The vanadium mine
[[[ in Arkansag ...... us£g ...... open pit methods to extract the vanadium ore.
             Mined vanadium ore is crushed, dried, ground, and screened to sizes less than 1.17 mm (-14 mesh).
                i                  '             .                    •        • •       "   . i  •   i       >         x
             It is men mixed with about 7 percent weight of salt, pelletized, and roasted at 850 °C (1,560 °F) to
             convert the vanadium to soluble sodium vanadate, NaVO3. It is then quenched hi water and acidified
      'f       with.' sulfiuic aqid to pH 2.5-3.5.  The resulting sodium decavanadate (Na<;V,0O2s) removes impurities
             such as sodium, calcium, iron, phosphorous, and silica.  Slightly soluble ammonium vanadate,
 ^        i NHtVQj, ........ is ..... precipitated from the ...... stripping solution with ammonia. The ammonium vanadate is then
             calcined to yield vanadium pentoxide, V2O5 (EPA, 1976).
                                                                          i
                » 7 »5
                                                                           .
            Aircraft ..... and ...... space ..... appjtfcations ..... account ...... for ..... 75 percent of titanium metal consumption, with the
                                                                   z ....... SHi ...... S&L ..... ?PPiications-
                                                     ), and ruffle (TiO^.  These minerals are found concentrated
               ^SsSSSifflSi	Sffii	feP°5!!5:	!?,	!.????>	only sand deposits of ilmenite were being mined hi the'u.S
            (Bureau of Mines, 1993).
                                                       	::	;	:	:'	I	:	:	'	:	:	'	:	:i
      J      The method of mining titanium minerals depends upon whether the ore to be mined is a sand or rock
            deposit.  Sand deposits occurring in Florida, Georgia, and New Jersey contain 1 to 5 percent TiO2 in
[[[ • hourj. No .hard rpck deposits are currently active.

           The land ore is treated by wet gravity methods using spirals, cones, sluices, or jigs to produce a
           bulk. ...... 2J»-*}» ...... JS^JSS! ....... SSfi316-  ** manv ^ five mdm*^ ...... marketable ...... .minerals,,,, are ...... then,
           separated from the bulk concentrate by a combination of dry separation techniques using high-tension
                       ..... SS ...... S^ff10 scpa^ofs, occasionally hi conjunction with dry and wet gravity
           titanium minerals from the silicate minerals. The minerals are fed onto a high-speed spinning rotor,
           and a heavy corona (glow given off by high voltage charge) discharge is aimed toward the minerals at
           the point where they would normally leave the rotor. -The minerals of relatively poor electrical
   	conductance arejunned	to	the	rotor	by	the	high" surface charge they receive, on passing through the
   I'III IH i  ill III 'illllliillliliilll lilililiiilllllliiliill	                                '     	Mil	ii::	iflillllSIl	!1W        	BBIIILIHpa*!	I	piffil1&fi«MSiSBtf!^S3B	ffl	illllll


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 EIA Guidelines for Mining     .   .                       Overview of Mining and Beneficiation

 high-voltage corona. The minerals of relatively high conductivity dp not hold this surface charge as
 readily and so leave the rotor hi their normal trajectory. Titanium minerals are the only ones present
 of relatively high electrical conductivity and are, therefore, thrown off the rotor.  The silicates are
 pinned to the rotor and are removed by a fixed brush.

 Titanium minerals undergo final separation in induced-roll magnetic separators to produce three
 products:  ilmenite, leucoxine, and rutile.  Separation of these minerals is based on their relative
 magnetic properties which, hi turn, are based on then* relative iron content: ilmenite has 37 percent to
 65 percent iron, leucoxine has 30 percent to 40 percent iron, and rutile has 4 percent to  10 percent
 iron.

 33.7.6    Platinum

 Platinum is one of the six closely related platinum-group metals (platinum, palladium, rhodium,
 ruthenium, indium, and osmium). Platinum and palladium are the most commercially important
 metals of the group; in 1992, an estimated 1,730 kilograms of platinum and 6,050 kilograms of
 palladium were mined.  The United States automobile industry is a major consumer of platinum for
 use in catalytic converters. Platinum group metals also are used in electrical .and electronic (29
 percent), medical (9 percent), and other applications (24 percent). Demand for platinum is expected
 to remain high as the use of catalytic converters increases around the world to control automobile
 emissions (Bureau of Mines, 1993).

 In the past, platinum mining hi the United States was mostly from placer deposits.  The only
 currently active platinum mine hi the United States is the Stiliwater Mine hi Montana; platinum-group
 metals also were recovered as byproducts of copper refining  hi Texas and Utah. Platinum and
palladium (at a ratio of 1:3) occur hi an igneous, strataform ultramafic rock at the Stiliwater mine
 (Stiliwater Mining Company, undated). The deposit is exploited through underground cut and fill
mining methods.  The ore is transported to the mill for crushing and grinding prior to entering the
concentrate circuit.  After grinding, the ore is added to the froth flotation units along with reagents.
The recovered concentrate is dried before transport to a refining facility for the recovery  of the
palladium and platinum. The mine received an amended permit in  1992 to double the mine's daily
production from 1,000 tons to 2,000 tons.

The tailings sluny-at the Stiliwater Mine is separated into coarse and fine fractions prior  to disposal
(Stiliwater Mining Company, undated).  The coarse fraction is pumped underground to be used as
sand-fill hi the underground mine. The fine fraction is pumped to a lined tailings impoundment. The
facility recycles water from the tailings impoundment back into the  mill. Very little waste rock is
removed during mining. Most of the waste rock is used to raise the dam of the tailings impoundment
when additional capacity for the tailings impoundment is required (Stiliwater Mining Company,
undated).
                                            3-101                             September 1994

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              Orel-view of Mining and Beneficiation , _ .••    _         EIA Guidelines for Mining
              _.            -    ,    .—                       .                           i   ;

              3.4     COALMINING
                                                                      .
                I     *       ;     ,                  -                         •
              This section focuses on surface and underground coal mining operations and environmental impacts
              unique to the coal mining industry.  Specifically, the subsections below addresses types of coal, .
             geographic ...... location ..... of coal, ....... and ...... nmmig ....... and ...... reclamation methods ....... is ....... the ..... primary ..... determinants ....... of [[[
             environmental impact. This approach was taken to isolate those areas of concern that are unique to
             coal mining activities and to establish a workable methodology to assess the. magnitude and  .
             significance of potential impacts.

             There are both similarities and differences between coal and other types of mining operations.  Any
             type of surface mining requires the removals of overlying soil and rock (collectively known as
             overburden) prior to the removal of the resource.  Coal and non-coal operations use many of the same
             techniques in the development and often in the production phase of mining. All mining activities
                 ......       ......             .....       ......        .......
             must ...... control ...... surface water ..... runoff, ...... nfimifiiTg ....... fugitive dust, and avoid impacts to the surrounding
             environment.  *-.,-—
             .   i              •-..      '      '"  ™"   -                        -                          •  ..... ;
             *   i      ,•          -  •         • "    •  ,     '•  •  .<   •      •-  ,-             ,         .  -   "• ..... - .......
             In addition to other environmental regulations, coal mining operations must .also comply with the
             Surface Mining Control and Reclamation Act of 1976 (SMCRA).  SMCRA greatly expanded the
             regulatory requirements placed on the operation and reclamation of coal mines (see Chapter 6).  One
             of the most significant aspects of this program is that of reclamation; areas disturbed by coal mming
             activities must be returned to approximate original contour and reclamation must be  conducted
             concurrently with mining.           ,
            3.4:1   • COAL FORMATION AND GEOGRAPHICAL DISTRIBUTION .
                i        ,                                      -
	' 3.4.1.1     Types and Composition of Coal                         *   .
llllllA	IIIH^^    •                             	lifH^^       	illH^^       	ii!	t^   	llM^               	I	>IIM^ "I	
  :          Coal was formed through the accumulation and compaction of marine and freshwater plants and
            "aniTtial^ living in ancient marshes.  The accumulated organic material was buried by sediments and
            altered from complex organic compounds to carbon.
            Coal is classified based on the percentages of fixed carbon, natural moisture, and volatile matter
                j ....................................... : ................................. : [[[ ! ............... ! [[[ ...........       '                               ............................. I .............. i .................... ; [[[
            present. Lignite, subbituminous coal,- bituminous coal, and anthracite comprise the major classes of
            coal. The percentage of fixed carbon increases, the percentage of volatile matter decreases, and the
            heating value increases from lignite to anthracite (see Exhibit 3-13).  Based solely on heating value,
            thepaxost value ofcoal can  e expected to ucreaseficom lgnte   anmracite.  gse suinir
            .. content and other, end-use specifications ...... aid ...... requirements ....... can ..... significantly ...... influence ...... tie demand for
SHBSBBS coal, the heating value is only one of several criteria that determine the actual market value of coal
                                                  ii,,                 i   ii	IIPTPIUIillii 1 ,„ :J	i!HI l.ll! IF: HlilWIIIIIIIIIIW^
           ^^^^^ •	jiii<<'              ^i'

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 EIA Guidelines for Mining
Overview of Mining and Beneficiation

Exhibit 3-13. Types of Coal and Relative Percentages of Constituents
Type
Anthracite
Bituminous
Subbituminous
Lignite , '.
fixed Carbon
(Percent) -. -
> 86 .
47-86
-42
30
BTUs/Pound
12,000-15,000
.11,000-15,000
9,700
6,600
Volatfles
(Percent)
< 14
14
34
25
Moisture
(Percent)
3
3- 12
23
45
\.

Sulfur is the most abundant trace element in coal, and reduces the value of those coals in which it is
found.  Sulfur occurs both as an inorganic constituent mineral (mostly in the form of pyrite) in coal
itself and as part of organic complexes associated with the deposit.  When the coal is burned, sulfur
.contributes to air pollution and reduces coking quality. When exposed to oxygen and water, the
inorganic forms produce add ™ne drainage.         .                '.
The sulfur content of coals found hi the United States ranges from 0.2 percent to about 7.0 percent by
weight.  The percentage of sulfur in coal generally is greatest hi the bituminous coals of the Interior
and Eastern coal fields. The sulfur contest of coal generally is less than 1 percent hi the Northern
Great Plains and Rocky Mountain Provinces for subbituminous coal and lignite. More than 90,000
million tons (64 percent) of the total surface-mmable reserves in the United States are low-sulfur and
occur hi the west.

Coal contains traces of virtually all elements. Burning coal results hi the concentration of most of
these elements hi the ash, although a few may be volatilized and emitted to the atmosphere. Arsenic,
barium, beryllium, bismuth, boron, cobalt, copper, fluorine,  gallium, germanium, lanthanum, lead,  .
lithium, mercury, molybdenum, nickel, scandium, selenium,  silver, strontium, tin, vanadium,
uranium, yttrium, zinc, and zirconium occur in some coals hi concentrations that are greater than
their average abundance hi the crust of the earth.

3.4.1.2    Coal Provinces

Six coal provinces (Exhibits 3-14 and 3-15) are defined hi the United States: the Pacific Coast,
Rocky Mountain, Northern Great Plains,  Interior, Gulf Coast, and Eastern.

Coal deposits hi the Pacific Coast province are found hi scattered fields.hi California and Oregon,  and
hi one large field and scattered small fields hi Washington. California coals are mostly of Eocene to
Miocene age,.and range hi rank from lignite to high volatile bituminous.  Oregon coals range from
subbituminous to bituminous.  Washington coals range from subbituminous to anthracite,  but most are
                                             3-103
                    September 1994

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                          11	1	
            Overview of Mining and Benefication
EZA Guidelines for Mining
                                 Exhibit 3-14.  Coal Provinces of the United States
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                                                     3-104
         September 1994

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EIA Guidelines for Mining
                                    Overview of Mining and Beneficiation
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                                3-? 05
                                                   September 1994

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           Overriew of Mining and Beneficiation      	     EIA Guidelines for Mining
               I             I                                      *               '
          subbipuaninous to bituminous; some also are of coking quality.  Coals in Alaska range from lignite to
          fight .volatile bituminous grades. Coals are found in large fields along the. Arctic Coastal Plain, and in
          smaller fields located both inland and along or near southern shorelines.

          The Rocky Mountain Coal Province is bordered on the east: by the Great Plains, and on the west by a
          series of high plateaus, including most of New Mexico, Colorado, Utah, Arizona, and parts of
         . Montana and Idaho, Scattered small  fields are found in central and southern New Mexico.

          High volatility bituminous coal is found ha rocks^of Upper Cretaceous age in the western Montana
     	'area. ^Coal	bgls	gig	thins	jngure,	and	usually	gSyd^storbedbyfoldhigand faulting.  The Big
 £     	ftm Basjg	coa|s	of Wyoming	and coal	found	in	extreme	southwest	Wyoming range in age from late
         Cretaceous and Paleocene, and is classified from lignite through high volatile subbituminous.  These
         deposits occur in lenticular beds which rarely persist at a minable thickness for more than 5 miles at
         outcrop. Dips of locally folded strata can ^^ 550 ^ resulting ^ ^ irregular distribution of coal '
         outcrop. The Paleocene age coals of the Hams Fork region range in rank from subbituminous to
         i%n volatile	bitumnous.	Beds	pnggherjrade	coals	may	be	as	thick as 20	feet;	thicknesses of .lower
         grade coal range to100 feet.  These coal beds are situated in a highly complex zone of thrust faults
         and folded rocks, resulting in steeply dipping strata and mereby making minhig difficult hi most parts
         of the region.                 •                                  .
         In c^p1 Wyoming (the Wind River Basin) coal beds are Late Cretaceous to Paleocene hi age, and
         aw aaoffly subbitumtoous.  Although coal beds may approach thicknesses to 17 feet, surface mining is
         m^i ...... jjjkultjjy the steep ...... djps of the strata. ................ ID ...... southwestern ..... Wyoming, coals range in rank from
         subbituminous to high volatile bitummous, and Mgher rank coak loc^y nay occur in areas of
  «       igneous intrusion and intense structural deformation.
                                             "
 111
        major beds up to 77 feet thick.  Coals found hi me Green River Region within the Colorado Plateau
        of Arizona, New Mexico, Colorado, and Utah, are generally found in horizontal strata of sedimentary
        origin-  Erosion of these strata has resulted in formation of canyons, mesas, and buttes.  The
        landscape comprises wide plateaus, uplifts, and broad basin areas. The Late Cretaceous age coal beds
  :      Hll^ UIB&. Coal Region range hi rank from subbituminous to coking quality high volatile
        bituminous; some semianthracite and anthracite deposits occur hi the Crested Butte Field of the Uinta
        Region.  Coal bed thicknesses generally range from 5 feet to 15 feet, but locally may approach 40
laSHIttSSJi	US	iSsSSiiSSSSS^RP^	aSe coals of me Southwestern Utah Coal Region range hi rank from
        subbitirainous to high volatile bituminous, with local occurrences of anthracite.  These coals are
        ft""*1 ^ fiat-lying to gently dipping beds from 2 feet to 30 feet thick. The Late Cretaceous and
        Eocene age coals of the San Juan River Coal Region occur as lenticular, discontinuous deposits up to
        5 feet thick in areas of complex geologic structure. Thicker, more continuous coal beds up to 38 feet

iiiti v in mmm  "	ii'i i ill	nil IH^^^     ii ^\im	i	iiiii'iiliiii	nil iiiiiii i11 ill IIP ii iv	ill	I* iiiiiiii1)'!  i liiii (iiiii'iiii	ill	ii iiw	i«11 • > in	IIIIIIIHII	in i	mi	
                                                    3-106                             September 1994

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 EIA Guidelines for Mining	       Overview of Mining and Beneficiation

 thick with numerous shaly partings are found in structurally less complex parts of this region.  San
 Juan River region coals are generally subbituminous, but high volatile bituminous coals also are
 found.

 The Northern Great Plains coal province the includes coal regions that occur in the Great Plains east
 of and adjacent to the Rocky Mountains. The area is characterized by little surface relief,, gently
 rolling plains, some areas of badlands and dissected plateaus, and isolated mountains.  Rocks of this
 province occur in nearly horizontal •sedimentary strata which curl up sharply along the flanks of the
 Rocky Mountains.  Coal found in central Montana is of Late Jurassic age and is high volatile
 bituminous containing 1.7 to 4.0 percent sulfur. Coals from north-central Montana are of Late
 Cretaceous age and range from subbituminous to Tu'gh volatile bituminous.  These coal beds generally
 are discontinuous and too thin to be of commercial importance, other than as sources of local fuel.
 Coal deposits found hi extreme northeastern Montana and western North Dakota contains an estimated
 438 billion tons of lignite, the largest single coal resource in the United States.  Coals are Late
 Cretaceous to Paleocene in age, and increase westward from lignite hi North Dakota to subbituminous
 in Montana. Coals found in southern Montana and northeastern Wyoming are Upper Cretaceous to.
 Eocene in age, and range from subbituminous to high volatile bituminous.  An 8,000 square mile area
 of gently rolling plains in northeast central Colorado are underlain by Late Cretaceous and Paleocene
 age coal bearing rocks.  Coals generally are subbituminous and occur in lenticular, discontinuous beds
 up to 17 feet thick.  Extensive deposits of lignite also are found in this region.  The coal found hi
 southern Colorado is of Late Cretaceous and Paleocene age and range from coking high volatile
 bituminous to non-coking high volatile bituminous.

 The Interior coal province is an extensive area of low relief underlain by flat-lying Paleozoic age
 sandstones, limestones, conglomerates, and shales which lie between the Appalachian Plateaus and the
 Rocky Mountains. Coal beds of this province are of Pennsylvanian age, and generally comprise high
 volatile bituminous grades which improve in quality hi the western part of the coal region.  In
 Oklahoma and Arkansas, some coal deposits have been devolatilized to coking low volatile bituminous
 and semianthrache ranks.

 The Gulf Coast coal province comprises extensive lowlands and coastal areas.  The subsurface
 generally is composed of unconsolidated beds hi detrital sediments and limestones which dip gently
 seaward. Outcrops of rock become successively older inland. The province has a good supply of
surface water and groundwater, and droughts are uncommon except hi southwest Texas. Coal
deposits consist of Upper Cretaceous age bituminous beds near the Mexican border, and extensive
 deposits of lignite which extend from southern Texas to Alabama.

The Eastern coal  province extends 800 miles from northern Pennsylvania to northern Alabama and
 essentially is mountainous for its entire length.  Coals of this province were deposited in the
                                             3-107                             September 1994

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            Orei-view of Mining	all	Benefication
                                                                       EIA Guidelines for Mining
                                                           11 UN 11,1 I
                                                            1 mi inn
                                                         i n  iiiiiiiii  n in nil i in iiiii i inn pi i iiii 11 win p in 111 iiiii i i n 11 n mini in n nil n 111  mini iiiiiiini 11  i mini n i in i mini in in  in n in
	,	i iii iiiiini iiiinin nnnnnnn iiiinni inn in in i in inn inn n nun n i  innnnnniinniiiini nun iiiigii nun n iniiininn niiiiniiiiiiiiiiiiiiiiiiiiiiniiiiiiiii nun iiiiiiini iiiiiiiiinni nun iiininn K
 Pennsylvankn age Appalachian Basin, which consists of a series of sandstones, shales, limestones,
 conglomerates, and coals.  Structural features such as faults and fold axes, trend northeast-southwest,
    II   ,      .  . ' ..  '-, 9  ,  , '  '           •  •••:	:-",	:	!	-";	:-:	I r-:	!	:	,	
 parallel to the basin margins.  The eastern part of the basin is extensively folded and faulted, and
    I    .    *    , i     '   i           •                                  I   '     i
 contains the higher grade coals of the region.  These coals  range in rank from medium volatile
 bituminous coals of the major eastern Appalachian coal fields to the high quality anthracite of
 northeastern Pennsylvania. The western part of the Appalachian basin is marked by strata in broad,
 open folds which dip gently westward.  Coals of the western  part of the basin generally are of the
 high volatile bituminous grade. The.ranks of coals in the Eastern Coal Province generally decrease
 from east to west in bands which trend northeast-southwest, parallel to major structural features.
 Ill 11 I IllM^^^   llllllllllllllIB     (i 111 A   Nlllilllllf IIIII •Illlill11 •IIIIIIIII illlllilll II I IIIIIIIII |l|||l|l ill IIIII Illlllllllllllllli 111 nil 11	lilllln illlllilllllll i  111 IIIIIIIII Ililllllin^^^^   lillllIM^^^^	1	I	I	I	|	
           3.4.13    Trends
           Trends in the coal industry are primarily driven by a change in the accessibility of eastern and
           western deposits and trends in the use of coal as a fuel, particularly in light of the Clean Air Act.
	These trends are
                           4.	:•
                         in the continued development of large, western surface mines as major
           suppliers of coal, while underground techniques are being more widely applied hi the east and
           midwest.	The	demand	for the	low sulfur	coals	that are	common throughout the west and the
           desulfurization of high sulfur coals for .use as boiler fuels is produced by increasingly stringent
           limitations on stack emissions on sulfur dioxide and participates.

           The coal industry will likely continue to grow at moderate levels within the foreseeable future.
           Whether the trend in increasing production from western operators continues may be based on the
           demand for clean burning coals. Western coals typically have lower sulfur concentrations and hence
                        than eastern coals. Howev
                                                ite and subbituminous coals of the west contain
           fewer	BTUs	and carry increased	transportation costs (either for the coal or for electrical power).
           Production	trends hi	the	surface	coal	.mining industry include (1) shifts of mining activity to coal'
           regions which	contain large reserves	of economically	recoverable and usable coal and (2) shifts of
           mining activity within regions to situations which previously were avoided because adverse
                       overburden thickness, or other factors precluded an economic return on investment in
    	'	•	ironing operations.	•	'	";	•	
                                                        '
                                       "I™™™                     .:::,. :!!:::::::::z::::::^^  	i;;
                   factors in	addition to the low sulfur content have contributed to the dramatic expansion of the
                   •-•-	'-—	==-	1==--	abots	of relativel	flat	land	"	
    »•"<	i	*	»	thick, horizontal seams, are amenable to Ugh production surface mining operations. The pit, spoil
           piles, haul.roads, and ancillary facilities can be designed to minimize the cycle times of unit mining
      	;	-.	operations, thus maximizing productivity per shift.

           Operators of eastern surface mines use such methods as mpuntaintop removal combined with head-of-
          I hollow fill	to	offset	ih	dgadvan|ages	of surface mining	in	steeply sloping terrain.  Although the
                                                                                                        	W
                                                                                             September 1994
                                                                                             •

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   EIA Guidelines for Milling	.	     Overview of Mining and Benefication

   extent and magnitude of their environmental impacts have been controversial, mountaintop removal
   and head-of-hollow fill will continue. The east has also demonstrated an increase in the number of
   underground mining operations to address the limitations established by topography and economics.

  3.4.2    SURFACE MINING SYSTEMS

  Surface mining systems are sequences of unit operations which have been designed to accommodate
  the limitations on mining imposed by geology, topography, and regulatory requirements.  Three kinds
  of surface mining systems are employed in the removal of overburden and coal extraction. Area
  mining and contour mining are by far the most commonly used methods, the third surface mining
  technique, open pit mining,  is used to a limited extent in southwestern Wyoming.

  3.4.2.1    Area Mining

  Two forms of area mining are conducted, conventional or strip mining, and mountaintop removal.
  Strip mining  is employed throughout the United States, primarily in the large mid-western and
  western coal  fields and to a more limited extent in the Eastern coal province. This type of mining is
  applied in regions with flat to rolling terrain where the coal seams lie horizontal or nearly horizontal
 to the surface.  Overburden in these areas is relatively shallow and regrading to approximate original
 contour is possible.  Mountaintop removal is used in ragged terrain of the Appalachian Mountains,
 where regrading to approximate original contour may not be feasible or desirable. Both methods
. essentially result in total recovery of the mined resource.

 A typical strip mining operation proceeds in the following manner (see Exhibit 3-16).  A trench (box-
 cut) is excavated through the overburden to the coal seam. This trench usually is extended linearly to
 the perimeter  of the permitted area, to the edge of the coal deposit, or to a location that
 accommodates future development of me mine.  The mined overburden (spoil) from the box cut is
 stockpiled parallel to the trench on unmined ground, and coal is recovered from the exposed seam.
 Successive cuts are made parallel to the initial trench, and spoil from each succeeding cut is placed in
the trench of the previous cut. Spoil from the initial cut is typically placed in the trench  of the final
cut. The disturbed area is progressively regraded to the approximate original contour and reclaimed
as mining progresses.  As required by SMCRA, approximate original contour requires the elimination
of all highwalls and other mining-related escarpments and depressions not needed to facilitate
revegetation and reclamation of the disturbed area.

The mountaintop removal method (Exhibit 3-17) does not return the mined area to the approximate
original contour as an entire mountaintop is typically mined through. This type of operation often
makes use of a head of hollow fill to handle the box cut spoil and any excess overburden. To initiate
a mountaintop  removal operation, a box-cut is made through the overburden along a line more or less
parallel to the  coal outcrop. This cut is made in a manner such that at least a 15-foot-wide barrier of
                                            3-109                             September 1994

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               T"

             Overview of Mining and Benefitiation
          EIA Guidelines for Mining
      	iiiiiiiiiiiiiiiii
I'lH
        ....... Ill
                                     Exhibit 3rl6. Area Mining With Stripping Shovel
                                                                  STRIP BENCH-  —   _   —
	:	•	        I                  i
m^^itmm iniiiiiii  i mi   iiiiiiiiiiiiiiiii i n iiiiiiiiiiiiiiiiiiiiiiiiiH^^^^  iiiiiiiiiiiiiiiiiiiiliiii1
                                                      IIIIIIIIIIIIIIIII 111 Illllllllllllllllllllllllll IIIIIII I   IIIIIIIIIII I III IIIIIIIIIIIIIIIII IIIIIII IIIIIIIIIII IIIIIII llllilM         .
                                                           3-110
                   September 1994
                                                ^^^^    lllliilliIlliIllllilllllIlM
Illlilllllli IIIIHIillll	llillli^                    	llliilliilB

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EIA Guidelines for Mining
Overview of Mining and Beneficiation
               Exhibit 3-17.  Mountaintop Removal With Head-of-HoIlow Fill
                                       3-111
                  September 1994

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            Overview of Mining and Benefitiation
                                                                              EIA Guidelines for Mining
           coal seam at the outcrop remains undisturbed. This "bloom" or "blossom" of undisturbed coal acts
           as a buttress to help stabilize spoil slopes during mining operations and subsequent reclamation.  Spoil
           from the initial cut is transported to the head of hollow fill or other approved stockpile area.
           Successive cuts are made parallel to the initial cut, and spoil from each successive cut is stockpiled in
           the trench of the previous cut.  Final stabilization and revegetation of the mined area can result hi flat
           to gently rolling terrain suitable for various uses.

           3.4.2.2     Contour Mining
               i                              .                                     •
           Contour mining methods generally are employed in the mountainous terrain of the Eastern coal
           province. Currently, contour mining makes use of one of three methods of operating: box-cut,
           block-cut, or haul-back.

           Box-cut operations resemble area mines (Exhibit 3-18) but make use of a smaller number of cuts,
                                                                                     progresses across
                                                                               ,  bulldozer clears  '
        l llllllIB Illllllllllll I III	Lj   ~_    .  -              -            "                     	'	!	I	
          vegetation from the box cut area and the area immediately downhill. As the initial cut is developed,
         |^*£^2i2	SSSii-SSSi	1S5S2SP ** outsI°Pe- Aft** coal is removed	from the box cut,
          overburden from the next cut is placed in the mined out area.  Operation of a dragline to place
          overburden into the mined out cut requires the development of a bench on the uphill (highwall) side
          of the operation. Operations making use of shovels and front end loaders can move overburden to the
          mined out cut without the development of a bench.  A barrier of undisturbed overburden at least 15
          feet w^de is typically left at the downhfll foot of the coal outcrop.
	?Zffi,	S2	SLiSEi'	i2?£	2SS	H	^?gned P313*161 with me c°al outcrop; mining •
mSt I	!«^ die nil within each cut and uphill in successive cuts.  Prior to the initial cut, a bull<
	u »ii»iiiiji|!i	 -    ..  .      .        .  .       _•_._.       '     	
                road and parallel drainage ditch are constructed along the coal outcrop and the exposed coal is
                    Often the unrecovered coal seam at the base of the final highwall is mined with augers.
                    maximum ^^ ^y ^ augerS) ^e ^^ holes generally j^, sealed wijh day or some
               nondeleterious, impervious material. The cut then is backfilled with previously stockpiled
         2»2?5f2	S	£f,	IP	SS	iSSSSSl	     	E	S2£fe	&),	5i	!?ghM'alJs *te eliminated, and (3) toxic and
         add-ibrming wastes and unmined,coal seams will not contaminate ground and surface waters with
         deleteljious siltation or leaehate. iBackfiU is regraded to the approximate original contour, where
         possible.  The regraded site is then revegetated with appropriate species of plants and monitored for a
         specified length of time to insure success of the revegetation effort.  Haul roads are either abandoned
	!	m »"• af^^blc manner or are stabilized for use during and after reclamation .(Gentry and McCarter,
	^992; Grm'anS	ISJ	19743.'	
                                                                             i         r n
         The development of a block-cut contour mine (Exhibit 3-19) is similar to box-cut mining, with major'
         differences in spoil handling techniques and the sequence of mining sections.  Whereas the box cut
    ilinSfi^Sls01161111^ P1006^8 "P and around a mounom m	one	direction,	block	cut	minjng progresses in
    'Sf fejbp^ directions along the coal  outcrop. An initial block of overburden is excavated near the center of
                                                 '	'"3-112
                                                                                       September 1994
                                                                                                                      I

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EIA Guidelines for Mining
Overview of Mining and Benefiaation
                       Exhibit 3-18. Box-Cut Mining Operations
                                                                   s
                                                                   i*
                                                                   I1
                                                                   o a
                                                                  Z e
                                                                  •= o
                                                                  o £
                                                                  £-0
                                                                  £§
                                                                  e
                                                                  to
                                     3-113
                 September 1994

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         Orerriew of Mining and Benefication
EIA Guidelines for Mining
ill!	IIIIIM
      i ill
      ivi
      I
  	Ill	Ill
                                    Exhibit 3-19. Block-Cut Mining Operation


                                              .  (SkeiiyandLoy. 1975)
                                               'Undisturbed Area

                                             Toosoil Applied /f±
                                              to Final Grade
                                                  2nd Step
                                                     3-114
         September 1994
                                             IlllllllllllllllilliillllilllIB
                                                                     lllllllllllll'flll

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  EIA Guidelines for Mining                               Overview of Mining and Beneficiation

  the permit area, and spoil temporarily is placed downslope of the coal outcrop, or in a head of hollow
  fill. The initial cut is two to three times larger than successive cuts. After the coal has been loaded
  out, spoil from the second cut is placed in the trench of the first cut. Because the second cut is only
  one-third to one-half .the width of the first cut,  spoil from the third cut also can be placed in the first
  cut. -The third cut is stripped as coal is loaded, out of the second cut.  In some cases, each successive
 cut is smaller than the previous cut, minimising the amount of spoil to be hauled to final the cut.
 Block-cut mining can also be .applied in area mining (Ramani and Grim, 1978; Gentry and McCarter,
  1992).         •      .

 Haulback mining can be used on smaller coal outcrops requiring greater flexibility than box-cut or
 block-cut methods.  In this method, rectangular pits are developed along the contour of the seam.
 The width of the rectangle (pit) is established by topographic or economic recovery constraints.
 Overburden from the initial cut is stockpiled in a suitable location. As successive pits are developed,
 spoil is "hauled back" to the previous pit by truck, scraper or conveyor.  The spoil from the initial
 box cut is deposited in the final pit. Reclamation occurs  progressively with the backfilling and
 regrading of each successive pit (Gentry and McCarter, 1992).

 3.4.2.3     Open Fit Mining

 The only open pit coal operation currently in production includes a combination of area mining and
 contour mining techniques to .recover coal from steeply dipping seams in the mountainous terrain of
 the western Wyoming. This operation is classified under the "Special Bituminous Coal Mines"
 category by OSM and is subject to special performance standards which closely parallel existing
 Wyoming law. Open pit techniques typically defer reclamation until the resource is mined out
 completely or to economic limits. This deferred reclamation for open pit methods contrasts with
 SMCRA's contemporaneous reclamation requirements.

 Equipment selection, spoil placement, and the depth to which coal will be mined are dependent on the
 ratio of overburden thickness to coal seam thickness (overburden ratio) and the number of seams to be
 mined.  Mining usually is initiated in the oldest (lowest) coal seam in the permit area.  A dragline or
 stripping shovel can be used to  cast  overburden  on both sides of the pit, forming spoil piles on the
previously mined highwall and adjacent to the outcrop of the next coal seam to be mined. Coal is
 loaded out with shovels or bucket loaders, and bulldozers reclaim the mined area to a configuration
 approved  by regulatory authorities.  Combinations of scraper loaders and stripping shovels also can be
used for overburden removal.

 Coal seams thicker than 70 feet with overburden ratios of 1:1 or less are mined by multiple bench
open pit methods.  Emphasis hi the  development of this mining method is placed more on proper
sequencing, of coal loading, hauling, and storage techniques than on overburden handling.
Overburden is removed from the initial cut by scraper loaders or a combination of shovels and
                                             3-115                             September 1994

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                               '    ;                                    .             <'        '
             Orcrview of Mining and Benefiriarion                    .             EIA Guidelines for Mining
            haulers, and is stockpiled adjacent to the pit.  Subsequent overburden cuts are backfilled into the pit
	!	*S	Sipping shovels load coal into haulers for transport to conveyors or unit trains.'' Both of these
••iJlBRfB transport systems' 'can feed preparation facilities or generating plants.	'	'
                 i             i     '   "                           '                       '
            3.4.2.4    Special Handling
                 |"   '	'«   	'"'   	;	:	:	:	:	:	                        •         i            .      .
            If segregation or selective placement of overburden horizons is necessary to achieve rehabilitation of
            the site to a particular post-mining land use, a combination of excavators, including scraper, loaders,
            draglines, bucket wheel excavators, and truck/shovel operations can be employed.  Pit geometry may
                 I                    •                                     i        .             ii
            be engineered so that excavators can pass one another during bidirectional mining. It also may be
            necessary	to	place	two	or more	excavators	on	separate benches to	achieve proper location of spoil.

            3.4JL5    Equipment

            The operational details of surface mines primarily depend upon the excavating, loading, and hauling
• JJ™"'equipment employed at the mine-site.  Equipment selection generally is based on the depth aid texture
lllllllllllllllllllll|l|||||il i iiiiiiiiiiiii i W    Hi iiii  '   i     i  in i   'Inn "I iiil1  111 11'  i    i i I in  n'  'i  ""   ii  '  ii        '    111 !"!!"!!"U!!!!!!L!!™!'"I?	I'l	"'	ITIS111!111!	j™'!!!!!!1'!'!!'!!'!!!!!!!!!!!!!!!!!!!!!!!!!"!!!"'1"!1!!	!	"""	"	»	IIS111"""	l!" 'i'1"!!!!!!"
            of overburden to be removed, the number of coal seams to be mined, the thickness of partings  .
111 lllllllllllllll Illllli' Illi illllll minimi ill •Illlllllllllllll I in in mllllllill in in i  ininninnnnnnnnnnnnnnnnnnnnninnnnnninniininnnnnn niiininn iiiiiiiiiiiiiiiiiiiiliiiiiiiillllliiiinllilll niiiiiiniliiiiiliniiiiini|inn n niiiiiiiiiiininn niiiiiinnniiii i »» iiiiiiiiiiiiiiiiiiiiiniiiiiiiiiiiiiiiii niiuiiiiiiiiiiiiini .iiiiiiiiiiiiiiiiiiiiiii iniiiniiii	i>iiiiiiiiiiiiiii,iiiiiiiiiinii niiiiiiiiiiiiiiiiiiiiiiini iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiii uuin innn iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii.iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiT'iiiiiiiii'iiiiiiniiiiiiiiiiHiin	n	mm	i	I	s	«	
           between multiple seams, the friability of the coal seams and die planned geometry of the pit.
	;	:	'"	!	;	"	'	"	"T!	;	:	'	'	:	:	':	:	;r	•	:	:	•	;	
                      used to remove overburden is based on the above criteria and  includes the following,
           which may be used alone or in combination:  draglines, shovels, bucket wheel excavators, front end
                 I1                       .'.'.«
           loaders, scrapers, and bulldozers.  Draglines and stripping shovels can be used if the overburden to
           be regraded in the mined-out trench orpit can be homogenized during stripping without adversely
           affecting the reclamation process.  Shovels and front end loaders loading trucks can effectively handle
                            selective placement in the backfill.  (Usually, a limited amount of special handling
                               '  IIIIIIIB lllllllR          llllllH^   IIII III  -     III llllllllllllllIM illllllll 111 Illllllllllllllllll lllitlH          ill Illlllll Illlllll Illlllll Illllllllllllllllllllllllll I ••Illlllll I I'lllll Illlllll Illlllll ' II  111111° 111
                            I a dragline.)  Scrapers are effective for removing shallow, unconsolidated
           overburden and bulldozers may be employed to prepare for benches or pads for draglines.
           Coal is transported from the mine she to cleaning plants, transfer points, and consumption points via
                        ^         i              ii                    i   i      i     111 i     i  i
           trucks and conveyors. Trucks used for coal hauling range in capacity from 25 to ISO short tons, and
                                     . Mobile conveyor belts are used hi some larger mines to
                                     	Ill ••      IIIIIIIH Illllllilllllll    Illlllllllllll 1111 111 I Illlllll Illlllllllllll IIIIIIIM^^           IIH^ IIIIIIIH^^	
                                     Permanent conveyors can be employed to transport coal from truck dump
iii iii i iiii 11 iiiiiiiiiiiiiiii  iipi in
           points to cleaning plants, railheads, barge points, and consumption points.
                               •                               '          :'      '  '•    :  ' ,  .. ....  !     ,il	    	''	

           3.43    UNDERGROUND MINING SYSTEMS

           Underground mining systems range in complexity from conventional drill-and-shoot operations to
IIIIIIH         IIIIIIH                                                 Illlllll	Iliil Illlllll IIIIIIIH^^^^                                  Ml Illillill Illlllll III lilldl 111 Illlllllllllll Hill	  Illlllll
           fully automated longwall systems. 'Summary discussions of mining systems (DOE, 1978;  EPA, 1978,'
           1976d, and'	1975) and comprehensive texts' (Britton and Linebeny, 1992'; Hittman Associates,' Inc.,
                    III Id ill Illlllll Ililllill III inillUli iillllillllllllllllllllllllllllli Illllllllllllllllllllllllll n Illllllllllllllllll III III 11 iiilnll II IIII IIII PP illiiill IIIIIIIIIIIII HI Illllllll hi
                                                           3-116                               September 1994

    Illllliii'i I' LI, 111(11(11	1	Ill) Illlllll 11 i"l In llNlilii '111 Wl	I'	IIII	I. IllliH  	II ,"111 ill" nil Ullllll"	•ill	Mi	Ill	(11 ilnHli i	Iil HI II",!,11 Ill	"Ill	I' ' Illllll	hi J   • mil •Jkl	MINIM i nll'il	11 '•	II'	1	I'*  •111 1	  1 ,n «ill ' lA III" U, 111 I if .ft ip
    	!	|	ilB11!1!	!	Ill	!	I	||	HI1!	I	I	I!	I	I	I	I	I11!	!	R	|	I!	ii	I	I1!	I	I'l11:1!	SB	IS1!	I!	,'"!'"!	I1"!1!	!"!!	,	I"!	i	I	Ill	I	I1!"!	'

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   EIA Guidelines .for Mining	      Overview of Mining and Beneficiation

   1976) describe in detail the technical aspects of the development, operation, and abandonment of
   underground coal mines.  This section presents an overview of underground coal production methods,
   including a brief discussion of each production method, and a general discussion of the environmental
   impacts typically associated with underground coal mining,

  As stated previously, underground mines account for approximately 40 percent of domestic coal
  production.  The majority of mis production comes from operations using room and pillar methods.
  Longwall mining operations account for approximately 25 percent underground production.  Shortwall
  minrng techniques are employed but only to a limited extent (McElfish and Beier, 1990).

  The following presents descriptions of underground mining systems using the minimum level of detail
  necessary to identify the sources of potential  environmental impact associated with underground coal
  mining                          .'        .                     .

  Lite new operations hi other mining sectors,  opening a modern underground coal mine represents
  planning, development, and intensive capital investment for several years preceding the profitable
  production of coal from the mine.  Underground mines are significantly more expensive to develop
  and operate than surface mines. Therefore they usually are planned for long-term operation in coal
 seams that are not recoverable economically by surface mining methods alone.

 The considerations necessary to put an underground coal mine into production, including
 development, ventilation, roof stability, and moving the coal  from the site of extraction to a loadout
 or cleaning plant, are similar to those of-other underground operations as discussed above hi Section
 3.1.  The buildup of methane gas within the mine workings is an additional concern unique to
 underground coal mining; additionally, in some circumstances, subsidence tends to be a greater
 problem than in other underground rnining operations. This discussion will focus oh those aspects
 where underground coal mining techniques differ from those employed at non-coal operations.

 3.43.1    Development

 The development or  construction of an entire underground coal mine may take decades, and
 extraction may commence in some parts of the mine years before development begins in others.
 While mine development is underway, the some coal may bee produced, however, the extent of
 production may be-minuscule compared to. the annual tonnages produced during full scale operation.
 Plans for mine development and extraction may change radically after mining commences, based on
 the availability of capital, innovative technology, and markets. However, after a operating plan has
 been approved and a permit issued, these types of changes must be approved by OSM or the State
regulatory authority as amendments or revisions to the current permit.
                                            3-117                             September 1994

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    I llllllll
                         II                            * '                         I                   k
                   •      ,          •                                      -   '   j-
               of Mining and Benefication	'     	    EIA Guidelines for Mining
    Mine development generally includes a standard set of operations beginning with the esteblishrnerit of
                                            2^4^ ..... techniques ......            '  ..... '                  ............



  ...................      ..... ,: ...............     ,,,   ......     ...... .......        ......        -, ......  ......         , ......   s,,0.!!^^?, sitng
    Tnadimery is" Used further develop entiyways 'and crosscuts, producing a hpneycornb of unexcavated
    c031 ^nd voids. The configuration of entryways and crosscuts depends on the strength and thickness
    of the coal seam and oy^urden, ........ the ..... amount ....... gf_subs|dence permissible, and the inernod used for
    recovering the coal (Britton and |Jnebeny, 1992; Hittman Associates, Inc., 1976). Roof control
    systems are installed within the entryways and crosscuts.  The specific method used for roof control is
     ..... Jjgjga ..... .ills ..... §S2££2ZJ2£S2! ....... != ...... S ..... 8555 ..... *5H£*2£ ....... d®Y?!°!»n5n!: ................ ISfe Pr°Ps> trusses,
                                              s are used to prevent roof falls.
    iUvQ	Inlll'l
               nnnnnniiiiiiiiinnniiijinniiiinnnnnnnn^^                                                               	vvjinniinnini! 11101191"",:, 11,	iiiiiiniiir,
         	Juubge, and electrical systems are installed as development progresses. One function of
       !,|a§2>2	ofjjHJais	and	barriers is	to minjmfze	the	cost of providing adequate ventilation to all
            areas of the mine. A minimum number of entryways and crosscuts also is necessary for
   rapid and efficient transport of coal from work areas.
                                       spptapnate	for	an	individual	mine	is	determined	on	.the	basis	'	:	

              tftbe	overburden^	sa&tv^recjjuirenient^	conservation practices, and workspace needs
                 In	fl»	jdeal	situatioiij	entryways and-crosscuts are .advanced through the coal seam to
                             be mined. Coal then is extracted from pillars and longwalls in retreat
        fej ....... in ..... tte ...... diregtios ..... opposite to the development advance).
                       '                            '
                 r°Pf properly, a generaUy symmetric system of pillars, barriers, abutments, and ribs
                     j ..... until ...... the ...... wttraction phase commences.  The dimensions and geometry of
  unexcavated features generally reflect men-.intended life spans and purposes, as weU as the strengths
  i	Snd	Sfcgl^?1	PJtpf??!"?	of the	coal	seam^and	pveAurden,	;	
      	f	

                                                   IS: ...... °£ ..... 525 ...... 3S2*SX*-
                                                                                   at an
           Jjf	choice	of vertical	shaft	versus	sloge	entryway usually depends on the proposed size of
-'	3.43.2    Extraction
                               HWlHBWlf!:!	C!f	i11"!"-*1!"1!
                                 is driven into a coal seam
                                 	;fj	
       ISi	222££»i	«iS5j2i	SSJfiSSSSS £i2S,,,E!3!	£2n2SSSi2i3l	SfePI	aid, sjjoot, .techniques or by
                          :	552J2I:	25EE	*°I,	5SE	!!2E!°P!!!E!5	55d,	coal production are chosen
                                                                   ,E?l, ,5???? .variables:
                         lillnlli UIIIPIIIIIIDIillll! I, !i III! Jlllllllill IKJIill ,'H^^^^^                     	HI''" II! M: l!ll!!lll!MilPi' «l U!!11	! 'I Hlilninnili MI'IBI	lllllllllllllaliililllllllllL!,	lllllllllyilillllllllllHIII	l!|linllli 11	Ill lIMlllIflUllili Vl"lllll«
                                                                          „	B.	September 1994

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 EIA Guidelines for Mining	Overview of Mining and Benefication


       •  Seam height, which determines one economic basis for choosing a mining system.
          Conventional mining systems become less efficient as seam height or thickness increases.
          Longwall mining systems are impeded by variations ha seam height.

       •  Bottom quality, which ranges from excellent (dry, firm, and even) to poor (wet, soft, and
          pitted or rutted), and affects machine operations by limiting traction and restricting
          maneuverability.         '
                                                                                  \

       •  Roof quality, which limits the amount of coal that may be extracted from the without
          artificial protection against collapse of the mine roof.

      •  Methane liberation, which in some seams occurs at a rate proportional to the rate at which
          coal is cut or sheared from the working face.  Methane accumulates and sometimes ignites
          hi underground workings when it is not removed by the ventilation system.  Methane
          accumulation is monitored at least once every 20 minutes at the seam face, causing
          disruption of otherwise continuous work cycles.

      •  Hardness of seam, which primarily affects the choice of coal cutting equipment.

      •   Depth of seam, which determines the response of the overburden to excavation of the coal
          seam.

      •   Water, which may infiltrate the underground workings  through channels, fractures, fissures,
          or other water transmitting voids in mine walls, roof, and bottom.


Conventional (drill and shoot) mining systems utilize five categories of unit operations (Hittman
Associates, Inc.,  1976) which can proceed simultaneously at separate working faces.  The categories
include:


     •   Cutting a slit or kerf along the bottom of the working face across its full length

     •   Drilling a pattern of blast holes into the working face

     •   Blasting the coal with chemical agents or charges of compressed gas

     •   Loading and hauling the fractured coal from the face to a centralized crushing and loadout
          facility for shipment to the cleaning plant

     •   Roof bolting with rods, trusses, props, and bolts to ensure the safety of underground
          personnel and to minimize the deterioration of roof conditions before a mining section is
          abandoned.


A typical sequence for mine development and extraction with conventional techniques is shown hi
Exhibit 3-20.  The flow of work depicted hi the figure is from right to left. Each numbered panel
represents an approximate 3 m (10 ft) thickness of coal to be extracted. ,
                                            3-U9                             September 1994

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                                       •illllllllll

                                                                                                            ^
 Overview of Mining and Beneficiation
                                                 • iiii 111 iiliilii mil in nil n i n iiiiiiii n in iiiiiii
                                                EIA Guidelines for Mining
                Exhibit 3-20. Operations in Conventional Room and Pillar Mining
IIIllHlllta
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lllllllllll!llllllilllllllllllll!l11111111 	 ll1™™™!!™™"'"


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107
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L Loading machine
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D Mobil coal drill
C Cutting machine
B Bolting machine
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                     3-120




lilH^^^^^            	IV
                                                                               September 1994
	Ill	'	Ill

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  EIA Guidelines for Mining           	     Overview of Mining and Beneficiation

  The cycle of unit operations in Exhibit 3-20 starts with coal loading and ends with roof bolting.  After
  the coal is loaded from Panel 1,  the bolting crew moves up to the face of Panel 8 to secure the roof
  over Panel 1. A coal cutting machine then is moved or trammed to Panel 8.  A cut 3 m (10 ft) deep
  is made in the coal seam with the machine-mounted blade, which is extended into the seam from the
  stationary machine.  The cutting blade is inserted into the base of the coal and is traversed across the
  width of the panel (usually 6 m or 20 ft); the blade produces a narrow kerf, or slot along the base of
  the recoverable coal.                                    .

  After the cutting machine is trammed to the next panel (panel 9),  the drilling crew cuts a specified
  pattern of blast holes into the face of Panel 8.  The holes are loaded with a blasting agent and then
  shot, exposing the working face of Panel 15. The cycle at Panel 8 then returns to loading,, and the
  coal is removed  from the face area ahead of the bolting crew.

 Continuous mining systems generally employ fewer workers per face and produce more tons per
 worker and per shift than conventional systems.  The efficiency of continuous mining systems remains
 essentially unchanged with increasing seam height.  Conventional systems reach a point of
 diminishing return as seam height reaches 1.8 m (6 ft).

 Continuous mining systems  use machinery to extract coal during room-and-pillar, shortwall, and
 longwall operations.  Machinery and panel configurations are chosen within the constraints of the coal
 seam variables described previously.

 Continuous room-and-pillar  operations are based on the capabilities of coal cutting machinery to
 combine the unit  operations  of conventional mining techniques (cut, drill, shoot,  and load) into one
 continuous operation; roof bolting may also proceed in conjunction.(and slightly behind) continuous
 mining.  The operation may be halted periodically for methane  checks and the installation of
 electrical, conveyance, and ventilation services. Coal is cut from the face with cutters, borers,
 augers, and shearers that direct the cuttings to conveyor belts mounted inboard on the machine
 assembly.  These inboard conveyors feed the coal to the mobile conveyor belts, shuttlecars,  or load-
 haul-dump (LHD) vehicles that transport the coal to the permanent haulage system, which may be
 another conveyor or a tram of mine cars pulled by a locomotive.

 Longwall mining  systems employ  one or more parallel entryways. located approximately 90 to  180 m
 (300 to 600 ft) apart arid connected by a cross cut (Exhibit 3-21).  The equipment necessary to
 conduct the operation including the cutter, conveyor, shield, and roof supports are inserted through
 the crosscut.  Coal is sheared or planed from the face and then directed onto die conveyor, which
 feeds the coal to a semi-stationary haulage system located in an  adjacent entryway. Roof supports
advance toward the cut face faydraulically, leaving the roof of the mined area (gob) to collapse as the
                                            3-121                             September 1994

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           •   Overview of Mining and Benefidation
Illllllllllllllllllllllllllll11 Ul""l	IIIFFI	I f FI'FI'I'I1 ln m^HmL*H*u*l***am***^—im*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^—
                                             EIA Guidelines for Mining
     1 illlTH illilli
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      iiiiiiiiiiiiiiiiiiii
   IIIIIIII' I Mil1
111 I IIIIIIII  IIIIIIIIIIH  IIIIIII
Exhibit 3-21. Longwall Mining System
                                                  3000-2 miles
                                                            i
                                      Collapsed  Roof



                                      Coal  in Place



                                      Mining Machine ("shear"  or "plow")



                                      Hydraulic Roof Support
                                                     Entry
1
                                  I IIIIIIII 111 IIIIIII Kill IIIIIIIIIIIIIIIIIIII IIIIIIII ll|l|l

                                  IIIIIIII I Ml I III IIIIIIIIIII IIIIIIII IIIIIIII I IIIIIIII 111 111
                                                                 ill n iiiiiii iiiiiiiiiii iiiiiiiiiiiiiiiii 111 iiiiiiii iiiiiii ill iiiiiiiiiii i| iiiiiii iiiiiiiiiiiii mi ill iiiiiiiiiiiiini iiiiiiiiiii
                                                             3-122
                                                       September 1994
             iiiiiiiiiii

                                     Illllll^

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 EIA Guidelines for Mining	.	Overview of Mining and Beneficiation

 unsupported overburden subsides into the mined-out chamber.  When longwall mining methods are
 used, there is a clear potential for surface subsidence, as described in section 4.8.

 Longwall systems are typically applied in situations where uniformity exists throughout the coal seam
 in terms of height, bottom and roof conditions, hardness, and areal distribution. Longwall mining of
 multiple seams is possible under some conditions. Shallow seams are mined first, followed by
 progressively, deeper seams. Overburden structures and lithologic characteristics influence the rate
 and form of the resultant caving and should be considered in the design/development phase.

 Longwall mining systems offer the following advantages over other mining systems (DOE, 1978):

      •  Lower cost per ton of coal produced
      •  Higher productivity per worker hour   .
      •  Higher percentage of recovery of coal resource
      •  Predictable subsidence
      •  Adaptability to thick and multiple seams
      •  Capability to mine at great depths.

Shortwail mining systems are similar in principle to longwall systems. During shortwall mining, coal
is cut from a panel approximately 45 m (150 ft) long.  Roof supports advance toward the panel as
mining progresses. The unsupported, undermined areas subside into the void behind the advancing
roof supports. The panel length is  short enough to be worked economically with the .conventional
mining machinery used in room-and-pillar systems, although automated shearers also are available for
shortwall systems.  .

Shortwall systems can be used to change existing mining operations from room-and-pillar techniques
to wall-type mining techniques without additional  costs for the replacement of machinery or revision
of plans for mine development.  Advanceable roof supports may be the only additional equipment
required to consummate the change-over. Shortwall operations also offer the advantage of flexibility
in selecting the locations of mining panels or walls to minimize the interruptions in production that
result from changes in seam height and the presence of want areas, unsuitable roof and bottom
conditions, and gas and oil wells.

3.4.3.3    Abandonment

The techniques that are appropriate for the abandonment of an underground mine generally reflect the
manner in which the mine was developed.  Water infiltrates to the mine void through overlying and
adjacent strata.  Drift entryways that are advanced up the dip of the coal seam will allow this water to
drain freely from the mine,  unless suitable seals are installed at the drift mouth. Entryways that are
advanced down the dip of the seam must be pumped during mine operation.  After abandonment,
                                            3-123                             September 1994

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                                                                                ,'	   "„    I1
             Overview of Mining and Beneficiaiion
                                                                                   EIA Guidelines for Mining
            ITlllii'l 1
                  lillllil'll
             water drains to the depths of the mine, forming a subterranean pool that may slowly drain to the
             surface through channels, fractures, and other small voids.
  inn
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                                of seals frequently are installed at mine openings during abandonment:

                                                                           •i ii	ti^	   •      ."    mil* nil (iiilil11" i Iiiiiii	mm\ fiiiliiiili11	I'liili
                  *   Dry seals to prevent the entrance of air and water into mine portals where there is little or
                                          minimal potential to develop hydrostatic pressure against the seal.
                    T|rseals'i) re|pce the flow of air into the mine while allowing water to drain from the
                     mine, Even these mines can still "breathe" through minute cracks and fissures because of
                     contmued changes in atmospheric air pressure. Enough oxygen usually is available under
                     these conditions for formation of acid drainage if sufficient pyrite and water are present.
                     Hydraulic seals which plug the discharge from flooded mine voids and exclude air from the
                     mine, thus retarding the oxidation of sulfide minerals.
           Hydraulic seals may be employed to seal the drift mouths of entryways that were developed up the
                               :6°
                | of concrete block, backfilled material, and grout curtains injected through boreholes from the
                    "~     "   "      I tffihnfques and others are thoroughly described hi other EPA
- =••	=	publications i(EPA,. 1973 and 1975).
                          11. "    ,»!, i               *            ,   „
                      2lES££S	iHY£	!SS	SSlSJl poUution control techniques used in the surface coal mining
        ™= industry.  Evolving technologies include:
                    Alternate mining methods, emphasizing controlled spoil placement and reclamation
                    '"«	5	!'"""	!!'	«	I!	'"	W1. •	"	S	 •	             *   *
                    conoirrent	with	extraction
                *   Sastewater treatment systems, emphasizing innovative techniques to replace limestone
^                                                 "Stoent ponds, both .of which suffer from reduced
       iiiiiit «^^^^^^^^
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                                                                 ions
                                                                                                         	
                                                                                                                !TiiiiiliK
                                        » gnipnasiTlng the replanting of reclaimed areas with plant species
                               been,spec1ally bred for replanting of local minespoils
                                            s emphasizing (1) the use of soil mechanics in slope design, and
                       soJlTOvering agents such as stubble mulches, cover crops, artificial soil amendments
                        .*.     ,._....,       ...      prevent ^{j 3^ water erosion of recently backfilled
                                        	
                         or temporarily stockpiled soils.
                                                                                       IIKlLillllli :ll!'l I'l'li'llliI'liiiiillili'iiainllJ.,'< 7"PIIIIIIPIilBlllllllllllirli'liI11)"'i'
                                                                                     111	laiiiiiiiiiiniiiiLiHiii
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-------
.   EIA Guidelines 'for Mining	     .	Overview of Mining and Benefication

   3.43.5    Environmental Effects      .                 . •

   The physical disturbance associated with surface coal mining and the surface aspects of .underground
   mining are the same as those of other mining sectors. Surface disturbance reduces the cover and
  primary productivity of the land. The loss of vegetation cover results in an increase in erosion and
  without adequate control, sediment concentrations are likely to increase in nearby streams.  Ground
  disturbance and constant movement by vehicles also increases fugitive dust carried in the wind. .

  Wildlife habitat is lost at least temporarily with surface disturbance while noise and  human activity
  create additional impacts in the immediate vicinity of mining operations. Although these impacts are  *
  to be expected with any mining or other surface-disturbing activity, they may be particularly acute
  when mining operations are being conducted on adjacent parcels of land over an extended period of
  time.                            •                            •

  Other environmental effects resulting from coal mines depend on the nature of the operation (surface
  versus underground) and to some extent, its location (east versus west).  In addition to the surface
  water impacts associated with most mining activities, surface coal mining operations may also impact
  groundwater. In the east, particularly,  acid mine drainage remains a problem .despite developments in
  the technology surrounding prediction and control.  Acid mine drainage  is discussed in Section 4.1
  and will not be discussed further here.  Subsidence is a response to underground mining activities.
  Although concentrated in the east and midwest, impacts from subsidence have also occurred in
  Wyoming and Colorado. A discussion  of subsidence is presented in Section 4.8.

  The extent of impacts to groundwater depends primarily on the premining hydrologic system and the
  chemical constituents of the overburden. As with other forms of surface mining, the geologic strata
 overlying the coal (or ore) are removed during extraction. Non-coal mining operations typically store
 this material in waste rock piles outside the pit while coaj mining operations are required to place
 overburden back into the mined-out portions of the mine.  As overburden is placed into the pit the
 hydrologic setting is changed from consolidated, heterogeneous strata to  a highly permeable,
 homogeneous mass.  The groundwater level and flow rate can be affected by the increased
 permeability of the backfill in the pit. The potentiometric surface will eventually stabilize, however
 the new surface may not reflect the premining water level.

 3.5    COAL PROCESSING

 3.5.1   BASIC PRINCIPLES

 Coal preparation is a-critical technology supporting both the mining and end-use of coal. The output
 of a coal mine consists not only of coal  but also non-combustible mineral matter. This mineral matter
 ranges in size from large rocks to extremely small grains dispersed throughout the coal seam.  The
 primary objective of coal beneficiation is the separation and removal of mineral matter from coal to


                                             3-125                             September 1994

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            Overview	of Mining	and Benefldation '            .    .                EIA Guidelines for Mining
                                   , ..... i .............           ' ......... ::„ ....... lEiiB^^^^ ............. in ..... 11 ....... Si ......... NIK .....         . ....... i ..... iiiiiiii: ...... •        ..... liiSid^^^^^^^^^^^  ....... 'Hans ......... :^,iii.ii:!!:S!i,i!!:!iii.  ..... :,: ....... :;i,,i ...... i:!)!:^^    is.it ....... Is ..... ±!]i!!!ii ...... sill
                                                     •       .
                                                          qj'jjg  hoacng in the biler
           JBurning coal with less ash increases boiler efficiency, boiler capacity, plant availability, and net heat
           ratCl, Reductions 'in auxiliary power ronsinnption, fo^gd ..... outages, ..... partialSe^e^sloK^ ...... aid ....... capital
           costs of new power plants all accompany the use of lower ash coals. Additionally, as-mined raw coal
           often fluctuates in quality and this is detrimental to boiler operation. Coal beneficiation produces a
                            .....       .....   ......        ......       .......      .....      ......           ........
           Concerns over the .environmental effects of coal bunung expanded the objective of coal beneficiation
           to include removal of inorganic sulfur in coal. More recently, researchers are examining coal
                                                   ..... '
                                                                                              ........ IflllViiSllSIBlplllllSllliliaHill'lllll'iiywhlll!1' ........ ifiinr vm ............. ll!!!1!11!!?!!!'"'!!:-''!!!!!!!!!11' ........
           preparation as a means of reducing air toxic precursors. As New Source Performance Standards
           (NSPS) were developed for coal-fired utility boilers/advanced coal cleaning technologies were    "
           simultaneously developed to remove 70 to 80 percent of the pyritic sulfur present in cod and recover
	li^	;	
           provided further impetus	for coal	preparation.	Utilities	could	now	choose	between several compliance
           options such as switching to premium low-sulfur coals, emission allowance trading, or post-
          ™r™^                                                                                              ',::;,:,:;::::: "ii:
           combustion clean up. Risk averse utilities could choose to pursue a mixed CAA compliance strategy
           because	of the	volatility of stand-alone •strategies.  Cod preparation became another viable option to
           meet compliance regulations	by its ability to convert high and medium-sulfur/ash coals'to low-sulfur/
                                                ,,mJn?Ii?l,,,,ma!ler, f*°m ?*w,594 a*6,	numerous and	the	•	
          configurations in which they are used hi cleaning plants can be complex. Despite the complexity of
          actual operating plans, there are only two underlying principles upon which all physical cleaning
          plants operate: (1) differences in specific gravity between the organic, combustible matter and the
         1    "•   '     ,:   ,!:!"!!"  ,!l!"ii,l  : ' '  * „    '   ""  •    ,          ,,',,.      • ,    ,'    :,,,•  ,   „ „'  „„ |, ,   ,, „     ',„.•„
                   	mineral	matte£ present	in	coal, and (2) differences in surface properties between organic and.
                    matter'.  Conventional coal cleaning processes are bas^i on-the" former principle, -whereas
          advanced cleaning processes are based on the later principle.

          Conventional	coal	gleaning involves the immersion of raw coal in a medium that simulates a
              : Jblib;
                        sgeclfic	giiviy.	-The	lighter	material is removed as a clean "float" product, while the
       ""iaviCT	material or "stok" ^rejected as refuse.  The majority of coal mined inthe United States is
          c|e|SM	BiSg tfiis^ jplriicipie.	A^small percentage of coal consisting of very fine particles-hi the raw
       ;	=P£^   	2522!	5*	£!??22!	22S	gawS^nKthods. iWithi fine particles m aqueous 'systems, surface
          forces become comparable with gravity forces and hence, gravity-based separation becomes
          ineffective.  Consequently, these fine particles, being only a small portion of the raw coal, are usually
         - discarded.	Alternatively,,	a	technigue taown as froA flotation inay be used to clean these 'fine
          particles.  Unlike specific gravity separation wnlch exploits differences hi the specific gravities of
          particles, froth flotation is based on differences hi the surface properties of coal and mineral matter.
          Coal surfaces are typically hydrophobic but the surfaces of the refuse material associated with coal are
                                                                                  HIP iiiiiiiiifipiin i,, iiipini, i' iiiiinipi,' ihliiiitii 11	iiipiii "i1	p i' i IP i nippipppi HUP iniipi j	ppiinninii 11 iihiiiiiiiiniPiipp iiiiinii PIIMPIIIPIIIIII i , pi iiiiiniiiipiy 11	h i iiiiiiipip'iiiiiiiiiiii
   iiiiiiiiiiiipijiii1 iiiiiiii'iii ''in iikii iiiiiiiiiiiiifii	ill iiiiiiiiiiiiiiiiii	iiiiiiiiiiiiiii iiiiiiiiiiiii i iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiR     iiii'iii," n	r 'nil 3-126                              September 1994

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  EIA Guidelines .for Mining                               Overview of Mining and Beneficiation

  hydrophilic.  By passing air bubbles through a coal-water suspension, coal and refuse particles can be
  separated; the refuse material sinks while the air bubbles attach themselves to the coal particles and
  buoy them to the surface where they are collected in a froth.

  The actual process of separating raw coal from its associated impurities, using either the specific
  gravity separation principle or froth flotation, is only one of the four processes that coal cleaning can
  involve.  The other three processes are crushing, screening, and dewatering.  Crushing serves to
 break down large heterogeneous particles into smaller, purer particles prior to separation. The extent
 to which crushing can liberate coal from impurities depends in large part on the depositional
 characteristics of the coal seam.  For example, if the impurities are finely disseminated throughout the
 seam, liberation may be relatively difficult.  If, on the other hand, the impurities exist as thick bands
 of rock within the seam, with weak bonds to the  coal, then the raw particles will tend to break along
 the weak bonding planes during crushing, resulting hi extensive liberation of the coal from the rock.
 In any event, the success of the subsequent separation process depends hi large part on the degree of
. liberation achieved through the crushing process.  All particles must report to either a float or a sink
 fraction during the separation process; thus, the existence of heterogeneous particles means that the
 clean float particles will contain mineral impurities, and the rejected sink material will contain coal.
 Coal cannot be completely liberated from its associated impurities through crushing—some
 heterogeneous particles will remain. Whether any given heterogeneous particle reports to the float or
 sink depends on the overall specific gravity (or, in the case of froth.flotation,  the overall hydrophilic
 tendencies) of the particle.                                                                       .

 Following crushing, but prior to separation, the raw coal is typically screened.  Screening is used to
 divide the raw particles into pre-defined size ranges. The various types of equipment used hi the
 separation process typically achieve maximum efficiency when processing feed of a relatively
.uniform, narrowly-defined size range.  For example, equipment based on the specific gravity
 separation principle fails below a mhiimnm particle size; for coal particles this is usually 25 mesh
 (575 microns) or 100 mesh (149 microns). For finer particles froth flotation must be used. Thus, the
 separation process typically consists of two or three separate circuits, each using a different equipment
 type designed to handle a specific size range of particles. Screening is used to direct the raw coal
 particles to the proper circuits.

 Finally, after separation, the clean coal and refuse are generally dewatered. Moisture, like ash and
 sulfur,  is an undesirable impurity; through the dewatering process the moisture content of the clean
 coal can be reduced.                                                                     .

 A perfect separation of coal from its associated impurities is not possible using either the specific
 gravity separation or froth flotation. This is because, hi practice the separation process is
                                             3_127                             September 1994

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         Overview	of Mining and Benefiaation
                                                                               EIA Guidelines for Mining
         fundamentally stochastic in nature. _ As mentioned earlier, some composite particles consisting of
                       and coilwllremaineven iaSecushin.
                                                                                                              • l   llnlllll ,, ,  'Ijj,
         Sulfur occurs in coal in both pyritic and organic form.  Pyrite is a mineral that is not an integral part
         of coal, but is normally associated with it. Hence, it is possible to separate coal and pyrite using a
        	I	J	!	:	i,	;	sti	;	!:!!	£	;	;;	_	;	1	;	l	;	;_	,	;_	;,	;	i	,	fi	;.	CIS.	
                          echmque.  Organic sulfur on the other hand, is an integral chemical component of
                          I	separated through physical cleaning.2
                                                                                       ^amount
        sulfur that	can	be	removed	from a given coal through physical cleaning is equivalent to the amount of
	Sills	oi^urring in pyritic form.    '                          '                            •
                                                                             , 	I	;	iW      	liyi'
                                                          '
                                                                                                  if. 'IHf
            degree to which the separation tails short of perfection is dependent on the raw coal qualities, the
                           -ami	5
        cleaning	equipment used, plant operating conditions, and the	washability of the coal. ' Coal
	  waspjabjj[t£	canjjejrou^£	defined	fajenns	of the	degree to wh^ a coal'can ^ gg^g^ fjouj ^
	  assc>ciate4',,,,impuritiesl'                 .          '          •
       lull	giii ill
       Raw	goal,	feed	consists	of particles combining coal and impurities in various;
        iiiiiiiiiii
                                                                                                 lii	iiliii	lilllf lilllil
                                                                                       tions; thus, the
       particles cover a wide spectrum of specific gravities. The washability of a coal defines this spectrum
•
       and consists of the percentage (or cumulative percentage), by weight, of the raw coal comprising
       contiguous specific gravity intervals, along with the quality (Btu, sulfur, and ash contents) of each
               gravity fraction.  Exhibit 3-22 is an example of washability data for a sample of a
       btaminous, high volatile A coal from the Pittsburgh bed in Jefferson County, Ohio.3  The data are
       divided into three size ranges of coal. • Within each size category, the percentages (by weight) of the
           (l83i ..... ,5J£ ..... it5^6® gravities less ....... than  1.3, 1.4, and 1.5 are given (e.g., 48.6 percent of the raw •
                           x, ...... lOg ..... irneshi ...... size, ..... |ange has a specific gravity less than 1.3).- ' Also, the Btu   •
           previous example, that portion' of the raw coal with a specific gravity less than 1.3 has a" Btu "
                 14146                    '
                                                       sample of coal is collected, crushed 'to a given

         organic liquids possessing^ definite, precise* specific gravities. The material that floats at each
                                                                                                   to
                ions example, 48.6 percent of the1V6 inch x 100 mesh sample floated when place in a liquid
                                                               	j
                                                                                            ^'illWIlHt:!' 'J;:!1!11'1!!)'!;
                      9111 be removed through chemical cleaning. However, chemical cleaning is not a commercially viable
                           !                                        '                        "
                       ililii?l,,;PP|S«^M:United .States Coals, Vol. 1, p. 395, Eastern Region, U.S. Dept of Energy.
                                                                                        September 1994
       n, '^niii iiiiiiiiiiiiiiiiiiij	.IHTI
                                              !;!',:	ini'ini	iniiiiij!, iniii'U	

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EIA Guidelines for Mining
                                                 Overview of Mining and Benefidation
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                                      3-129
                                                                   September 1994

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  Ill III
                                                                                                                   111' 	Ill
                       nf Mining and Beneficiation
                                                                                     EIA Guidelines for Mining
            witii a specific gravity of 1.3; this "float" had a Btu content of 14,146 (per pound basis).  The
            specific gravity of the bath (1.3 in the example) is referred to as the specific gravity of separation.
                                                            i  '            ,,,,|"
                i,     •'      .....                       '  '         "   '
      1      Commercial cleaning plants achieve gravity separations by employing various techniques (including,
            e.g., suspensions of ground solids in water) to simulate the heavy liquid media used in the laboratory.
            The behavior ..... of a coal ..... sample ..... in ..... a ...... laboratory ..... bath, as ..... measured during ...... washability tests, ....... provides ..... a ...............
                                                                                              .               .
         ..................... • ........ theoretical ..... limit ..... of how the coal will behave in a commercial' cleaning plant.4 Washability data, like
            those presented in Exhibit 3-22, are used to estimate1 the yield and clean coal' quality for a given coal
            cleaned at a given specific gravity of separation. For example, if the 1 1A inch x 100 mesh coal from
            the earlier example is to be cleaned at a specific gravity of separation of 1.6, Exhibit 3-22 predicts
            basis), an ash content of 7.5 percent, and a total sulfur content of 2.54 percent. Commercial cleaning
            plants	rarely	reach	these	theoretical	levels	of product	quality.  Computer models	for	simulating	coal	
^™|	       preparation	can'	be	used to estimate commercial plant performance.' Such"models use washability data
            to predict the yields associated with cleaning various coals to meet predefined quality specifications.
Hi !•    	ill!	Ill	lil	           .           	         .     	1^^	mifi	Plilllll	Ill*	Kill! illillV         	1	•	I	•Ill	I'n'l	
            An important characteristic of all washability data is this trade-off between coal quality and quantity.
            From Exhibit 3-22, for all three particle size fractions, Btu content increases and ash and sulfur
                  nn mini i mm mi i mm mini i in mini nn inn in
                                 ,                                       „          .
  •         The common way of assessing or evaluating coal cleaning systems that use gravity separation
           techniques is to determine the sharpness of separation achieved.  This is done using partition curves.
           The partition curve of any given equipment that separates coal and mineral matter is essentially a
............................................. ............ i ................. ..................... histogram of the distribution of coal groups of different densities hi the product.  Typically the
......................... " ............ ............. ' .................................. histogram is represented in the form of a cumulative curve with the partition coefficient on abscissa
                                                 U   *
................... iii [[[ in the curve is parallel to the abscissa at the density of separation .  The partition curve is typically
•ii^       characterized by two parameters dp and e,.  d. is the relative density corresponding to partition
III Wlllllllllllll I Illilllllllli I II IIIIIIII IIIIIV Illllnl III illlllllllllll llllllllllllllllllllllllll llllllllllllllllllllllllllllllllllllilliiiimll lllllllllllllllllllllllllllllllllllllllllllliii i Hiiiiiiiiiiii nn 1 1 innnnnnnnnnnnnnnmnn mm i innimiiiiiihn mm "      i*   t*
........................... ; [[[ coefficient 50. .............. This is ...... the relative density at which an infinitesimal increment of raw feed is equally
                                                                                                                   i ............... in
           content decrease as the yield decreases. Thus, improvements in coal quality can be obtained only at
           the expense of reductions in yield; this is true of all coals including the sample represented in Exhibit
           3-22.  Not only are mere technical limits to the percentage of ash and sulfur that can be removed
           from coal through cleaning, there are economic limits as well.  For example, referring to Exhibit
              1  i*iii                    i                                i
           3-22, we can see mat it is technically feasible to reduce the sulfur content of 1V6 inch x 100 mesh
           coal to 1.82 percent; however, the resulting yield would be 8.6 percent.  From an economic
           standpoint, it is unlikely that the benefits obtained by reducing the sulfur content to 1.82 percent
           would outweigh the costs associated with the loss of 51 .4 percent of the coal.
linn iiiiiiiiiiiii i inn nil i mi n n inn linn iiiiiini inn inn ninnnnnnnnnnnnnnnninininn i nnnnnnnnnnnnniin innnnnninn mini niiiiiiiiiiniiiiiiinnin iiiiigiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiininn niiiiiininn in niiiiiiiiiiiiiiiiiiiniiiiiiiiiiininn niniiiiiiiiiiiiininiiiiiiiiiiiiiininnnnni i iiniiniiiiiiinnnnn in i niiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiiiiiniiiiiniiiiinninin mini iiiini mi inn        i  i   i             i i        i
              ^Laboratory washability data represents separation at ideal (equilibrium) conditions, whereas separations in an actual
                  not have sufficient time to reach equilibrium and conditions for separation are non-ideal.

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EIA Guidelines for Mining
Overview of Mining and Beneflciation
                           Exhibit 3-23. Washability Partition Curve
                                         0
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^^^~u	i	;	;	i	
             Overview of Mining and Benefication
                                                                          EIA Guidelines for Mining
           r illlliillllllll ii
                       Ililllllliiill
                                111 illlliillllllll HI
             divided between clean coal and refuse.  ep> the probable error, gives an indication of the deviation
             from ideal separation and is calculated as the slope of the curve around; dp.  ep is also a function of the
            panicle size and the density of separation.  Each equipment hi a coal preparation plant operates at a
           liiLlllllll Illllll fllllM^                             III IK illlliillllllll 111(11 II III lllllllIllllllllllllliiil ill ll i ll I ll lllllll ill illlliillllllll ill lllllll lllllllllllllliiiB	 	i	i	 	 i	
•^"^^1^ particular*^ and
                               	i	
                                                                   II I V 111 I I lllllll lllllll II
            Although washability data provide an indication of how coal will respond when cleaned using gravity-
            based equipment, they do not indicate how .coal will respond to surface-based separation equipment,
	such as froth floatation.      '•              '             '                  '             "
            Coarse ore tailings or coal refuse can be used to construct an impounding dam, typically within a
           • rira?T13geway or narrow valley.  Then, a slurry of finer tailings or refuse can be pumped" into the
            impoundment area for settling (similar to tailings impoundments described for metal mining above).
            As with	other tailings	impoundments,	these	can be quite	large,	with	impoundments	reaching	over	100
            feet high and 1,000 feet long.  Both NPDES and dean Water Act §404 regulations can, in some
            Situations, prevent'the construction of such impoundments.  When they are allowed, the major
    '":	!":	;":":"i:	" environmental	concern	is the destruction of the drainage that	is being filled.	'States generally 'require
            that existing instream uses of surface waters be protected and maintained (generally known as "non-
            degradation" policies), and these often prevent such:

                     COAL CLEANING TECHNOLOGY
           EPA has an ongoing research and applications program that may significantly affect the future form
           lid economics of current and developing coal cleaning technologies (Section 1.3.3.). Reports of this
           program describe in detail the coal cleaning technologies currently used by the mining industry
           (Nunenkamp, 1976; McCandless and Shaver, 1978}.' The engineering principles of mechanical coal
           cleaning also are described more thoroughly in orner sources (Leonard and Mitchell, 1968; Cummins
           and Given, 1973; Merritt, 1978).  The following discussion of coal cleaning technology summarizes
           the elements of mechanical coal preparation in the detail necessary to identify the impacts and
           pollution control strategies associated with proposed projects.
                                                 ,
           The mechanical	cleaning of coal generally includes the five basic stages (Exhibit 3-24) described .
           below.  The number of stages employed and die unit operations that comprise each stage may vary
           among individual operations; atthough Stages 1, 2, and 3 are common to most of the Nation's coal
           c|eamng facilities (Exhibit 25).
                                          ii iiiiiiiini 11 iiii ill nil mill i	r ii i
1:1(11!
                     Stage 1—Plant Feed Preparation. Material larger than 21 cm (6 hi) is screened from the
                     ROM coal on a grizzly.  The properly sized feed coal is ground to an initial size by one or
                     more crushers and fed to the preparation plant.

                     Sfg* 2—Raw Coal Sizing.  Primary sizing on a screen or a scalping deck separates the
                     coal into coarse- and intermediate-sized fractions (Exhibit 3-26).  The coarse fraction is
    i i ii iiiiii iiiiiiiiiiiii ii
               (•Ilillll 	((Illllllllllllliiil
                                                 3-132
                           mil 1	Ill	lillH       	liliililll I11 (111 111 1111 ll	I (i !i J
                                                                                           September 1994
•iiiii	ii i iiii Fiiii iiiii iiiiii	iiiii  •	i	i	i	1	iii	i	i	|	ill

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 ETA Guidelines for Mining
               Overview of Mining and Beneficiation
                  Exhibit 3-24. Coal Preparation Plant Processes
   PLANT FEED
  PREPARATION
Rtm OF MINE STORAGE
      3
      z
 RAW COAL
   SIZING
 RAW COAL
SBfeRATION
  PRODUCT  WATB"
DEWATERING
   PRODUa    I
   STORAGE
AND SHIPPING
                               3-133
                             September 1994

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                  I                   ll

               Overview of Mining and Beneficiation
                                                                                                                   1	mmi
EIA Guidelines for Mining
            	1
                feK
  lllllllllllllllllll 111  (II 111 lllllll
111 IIIIIIH lllllll lllllll

II1II1H
IIIIIIH
                                                                                                                      I
                                                                                                                      e£

                                                                                                                      |
                                                                                                                      a
                                                                                                                      i
                                                                                                                      wa
     Illillllllll Ilillillllllll	|i|||ill III 11 illllllllllllH  in llllillilill llllilH^^    i l|||||||||||||||||||l||||
                                                                                 i
                                                                3-134
           September 1994
                                                                                                    "  II

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EIA Guidelines for Mining
Overview of Mining and Beneficiation
                    Exhibit 3-26. Typical Circuit for Coal Sizing Stage
                                             :^mwAW$s$»/R.R. CAR
                                      3-135
                 September 1994

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                                                                             iiii in  in in n iiiiiiiiil 1 1 iiiiiii i mi niii in in 1 1 ill i iiiiiii  1 1 iiiiiii in i  i i Hi* 1111
                                                                                                                        iiiiliiiiiiiiii
             Overview of Mining and Benefitiation
                                                                                     EIA Guidelines, for Mining
                      crushed again if necessary and subsequently is re-sized for cycling to the raw coal
                      separation step.	""Tie"	intermediate fraction undergoes secondary sizing on wet or dry
                    ; yjlfra^ng screens to remove fines, which may undergo further processing.  The intermediate
                      fraction then is fed gpjthg^v/gsa! separator. Coal sizes generally are expressed in inches
    	11	or mesh' size (Exhibit 3-27).  In Exhibit 3-26, the notation 4 x 0 indicates .that all, of the
                      coal is smaller than 10 cm (4 in).  A notation such as 4 x 2 indicates that the coal is sized
    	[	;	Igfweea	^andJO^m (2 and 4 in). The notation 4+ indicates that the coal, |s larger than
                      10 cm (4  in).    	             .                   ":	•"'	
"
in hi 	 mm
IIH^^^^
iiiiiiiniiiiiiniliiinn i ii iiiiiiiiil iiiiiii in 11
i
,' '• , •
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIILillll1 IIIIIIIIIIIIIIIIIIIIIIIHIIIIIirlllllllL


	 ., 	 . 	
^^^^^~™
=ss::fsf™
iiE^^^^^^^^^^^^^^^^^^
• 	 	 • 	 • 	
	 ; 	


Ill: Illllllllllllllll i,II 	 lllllJlliiri:,:"!!

= 	 =.

Exhibit 3-27. Metric and English Equivalents of U.S. Standard Sieve Sizes and
Tyler Mesh Sizes
BiS. Standard Sieve
••'-•':. No.
4
6
8
10
12
14
16
18
20
30
35
40
45
50
60
70
80
100
120
140
170
200
230
270
325
" v*< MediSize •'">••./: • .
) CHI
.475
.335
.236
.200
.170
.140
.118
.100
.085
.060
.050
.0425
.0355
.030
.025
.0212
.0180
.015
.0125
.0106
.009
.0075
.0063
.0053
.0045
indies >
.187
.132
.0937
.0787
.0661
.0555
.0469
. .0394
.0331
.0234
.0197
.0165
.0139
,0117
.0098
.0083
.0070
.0059
.0049
.0041
.0035
.0029
.0025
.0021
.0017
'
' .•:•: ;. V..^.:'; ' *, • ..: , . \}%;_ V'.' .'."•
Tyler Mesh No;
4
6
8
9
10
.12
14
16
20
28
32
35
42
48
60
65
80
100
115
150
170
200
250
270
325


                                      111 111 II II
                                      II fill IIIIIII
                                                  Ill 111 IIIIIII
                                                ll 1111111II	
                                                                                     iiiiiii nil iliinni 111 ii i 11 ii 11 ii ill nnii iiiiiii nil iiiiniiii in n    in
	,	,	,,	,,	_,„ _	 • .	.	.	•	,	,	_	  (                         (        ! 	I	'	
™                            Coal Separation.  Approximately 97.5 percent of the U.S. coal subjected to
             	~=	=l"""~*       ""     "           : processes, including dense media separation, hydraulic
                               	and_frojh	flotation.	Pnejnnatic	separation is applied to the remaining 2.5 percent
     ™™-' 19785).  The coarse-, intermediate-, and fine-sized fractions, are processed separately
^^i^f^'J-^sli^	equipment uniquely suited for each size fraction..  Refuse (generally shale and
                                middlings  (carbonaceous material denser than the desired product), -and cleaned
                                       °
••^^    	ii i-niu	_
•B^^^^^^       	11^^^^^^^^^^^        	9M^                         	
•IIJH^^^^^^^^        \!«IKP]II|H   	lliilliin^^^^^^^^
!!!!!!•        "'''Fill1*1 ili'f
lB^^^^^^^^^^^
                                                                                      	I,11 f ISiOM^^     	IIVIIPfllllKnlK',1'!
                                                                                      "iiK	B	iiii	ii;:n^^^^^ 	ilia	
                                                                               jiiSM^^^^              	illllllta^^
                                                                ^   	ii.!:!;')*,!!!','!'	silt! iiii;!r-ii:i\
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  EIA Guidelines for Mining
Overview of Mining and Beneficiation
       •   Stage 4—Product Dewatering and/or Drying.  Coarse- and intermediate-sized coal •
           generally are dewatered on screens. Fine coal may be dewatered in centrifuges and
           thickening ponds and dried in thermal dryers.

       •   Stage 5—Product Storage and Shipping.  Size tractions may be stored separately in silos,
           bins, or open air stockpiles.  The method of storage generally depends on the method of
           loading for transport and the type of carrier chosen.

 For a typical coal cleaning plant with 910 MT (1,000 T) per hour capacity, approximately 70 percent
 of the crushed coal reports to the coarse cleaning circuit.  Sizing and recrushing of the coarse coal
 result in the cycling of 34 percent of die coarse coal charge to the fine and intermediate cleaning
 circuits.  Approximately 27 percent of the coarse charge is removed as refuse.  The remaining 39
 percent is removed as clean product.  Process quantities for the fine and intermediate cleaning circuits
 appear in Exhibit 3-28.                                            •
<
Exhibit 3-28. Typical Process Quantities for a 910 MT (1,000 T) per Hour
v Coal Cleaning Facility
;;; 't <>-^ ,-' ,-
,',"•' * ^ •. y
,,* - - ' - / r% % -
Coarse coal fraction
Intermediate coal fraction
Fine coal fraction
Thermal dryer dust
Total
.;' Washing
Circuit
MT/hr
630
190
90

910
%
69
21
10

100
•• Dewatering ••-
Circuit
MT/hr
245
330
58

633
%
. 39
52
. 9

100
'Process-. i.':,:.-.:"
Water^*':-:-':v
MT/hr
, 3,293
7,040
16,427

26,760
f v %: .
12
26
61

100
•.s..,,: 'Refuse^ .£ ./
'.'•v Recovery -::>s.'-..
MT/hr
173
82
19
•3
277
^•••:%. "•••••
63
30
6
1
100
Source: Nunenkamp, David C. 1976. Coal Preparation Environmental Engineering Manual EPA,
Office of Research and Development, EPA-600/2-76-138, Washington, D.C., 727 p.

3.5.2.1    Stage Descriptions

The initial screening and crushing of ROM coal at Stage 1 (Exhibit 3-24) may be accomplished in one
or more substages (Exhibit 3-29). The grizzly can be a set of iron bars, welded on 21 cm (6 in)
centers to a rectangular frame.  Oversized material that would otherwise inhibit the operation of the
primary crusher is scalped from the feed coal on the grizzly bars. In a multicrusher system, the
output from the primary crusher is screened. Over-sized coal is fed next to a series of crushers, and
finer material reports directly to sizing and separation stages.
                                            3-137
                    September 1994

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        I	Overview of Mining and Beneficiation
                                                               EIA Guidelines for Mining
                                  1 illiwin in iiiiiiin niniiiniiiniiliiini  niiiinin IIIIIINIIIIIIIIIIIIIIIIIIIIIIIIIIJ* n iniiiiiiiiiiiiiiiiiiiiiii in  i iiiniiinin i n iliillini inline     i ill lllliiiiiiiiiH        i  iiiilin in• innin mi HIM 1111 niiiiiiiiiiiiniiniiiiinnniii
                                  iiiiiiiliiiiiMiiiiiiiiiiiiiiiiMiiiiiiii in  nil 11 n inn in i nniinniniiniinnini i ininiiiniiiiiniiiiiininni ni» n   i     i  nn n 11 in ii  in  n • |i in in i  nl   HI j
                     Exhibit 3-29.  Typical Three-Stage Crusher System for Raw Coal Crushing
                  £,,,S2S ...... 22 ..... X ...... £2JS!S,IS,2l?ge l CfasW^ include rotary breakers, single and double
        roll Crushers, hammermffls, and ring crushers.  Each type of mill is available in various models which
        crush the ROM coal at different rates to different sizes.  The general characteristics of crushing mills
        appear below (McQung, 1968).
'!" ! ....... «•««« ,'!,"
' ....... Mil ftl i
      .  breaker.  Often called the Bradford breaker after its inventor, this large, rotating
cylinder is driven at12 to18 revolutions per minute by an electric motor via a chain and
reducer drive.  RO|| cgal |§ilssiucMithrough one end of the cylinder and is crushed
against tne encirc|ing steel plates.  The crushed coal exits the breaker through the precut
holes nj the plates and feeds to a conveyor. Slate, overburden, rock, and other gangue
materials that resist breakage are carried by a series of baffles to the far end of the cylinder
Where they are removed from the mill by a continuously rotating plow.
               •i ii iii 11
              1   Single-and Double-Ron Crushers. A roll crusher comprises one or two steel rollers
 	I	gB^* i^11 two	SUSS!	Ispgths of heavy teeth.  The long teeth slice the large pieces of
 	I	W mtp fragments and feed the flow of coal into the smaller teeth, which make the proper
                 ^reduction. In single-roll mills, the coal is crushed against a stationary breaker place
                 (Exhibit 3-30a). Double-roll crushers also fragment the coal with specially designed teeth
 	Crushing action against the rollers (between the teeth) is minimal (Exhibit 3-30b).  Both
            I     nulls are fed through the top.  Product exits through the bottom.
11 Mil III IIII III II II II  I III 111 III I

in nil in in i ii ii ii nil  11 iiiiiii
                             in i n n n n in nn i nn in i i n n 11 n in i in Mini

                             III ill III III I i III 111 III I III  III II ill III
                                   3-138
September 1994

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EIA Guidelines for Mining
Overview of Mining and Benefitiation
      Exhibit 3-30. Single-Roll (a) and Double-Roll (b) Crushers for Sizing of Raw Coal
 Source:  McClung, J.D., 1968. Breaking and crushing. In Joseph W. Leonard and David R.
 Mitchell (eds.), 1968.
                                        3-139
                   September 1994

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            Overview of Mining and Beneficiation
                                                                                EIA Guidelines for Mining
	i	i	,,i	grate and discharged to a bin or conveyor.
                     Ring crusher.  The principles of hammermill and ring crusher operations are similar.
                     Instead of hammers,  the ring crushers uses a set of smooth and toothed rings to drive the
                     feed coal against the breaker plate.
            The unit operations that commonly are employed at Stage 3 of Exhibit 3-24 (separation) vary
            considerably among, modern cleaning installations nationwide.  The choice of unit operations for a
            particular installation depends on a number of factors, including coal preparation objectives,
           ' availability and costs of equipment, and operator *ixperience.  Nile of the typii
           currently are employed during the separation step are listed below (McCandless and Shaver, 1978).
           With the exception of froth flotation, all of these operations utilize the specific gravity principle to
           affect a coal/impurities separation!  Water requirements, sizes and rates of feed, and dewatering
                      of selected unit processes are described in Exhibit 3-31.
                             '-                  	ifi'nBI'IfiiHii
                     Dense Media. Light, float coal is continuously skimmed from a suspension of solids in
                     	that	separates from heavy liquid with a defined specific	gravity	(usually	magnetite;
                     Exhibit 3-32). Finely-ground magnetite is usually used in the suspension, in part because it
                     can be easily recovered from the clean coal and refuse by magnets. - Accuracy of separation
                     is sharp from 0.059 to 20 cm.  Quality and sizes of feed can fluctuate widely.

                     Froth Flotation. A slurry of coal and collector agents is blended to induce water-attracting
                     tendencies in selected fractions of the feed coal.  After the addition of a frothing agent,
                     finely disseminated air bubbles are passed through the slurry. Selected coal particles adhere
                     to the air bubbles and float to the surface, to be skimmed off the top. The process can
                     separate fractions in a band of 0.045 b 1.18 mm (0.002 to 0.05 in).  Froth flotation affects
                     a good separation between coal and ash, but does not successfully separate coal from pyrite,
                     because the latter mineral is, like coal, hydrophobic. Better sulfur reduction results can be
                     obtained using two-stage flotation.  The first stage proceeds as described above. In the
    ==^           second stage, the float product is re-slurried and then treated with an organic colloid that
    	;	sl	"''•	:'	'	'	'	selectively prevents the coaTplxticites	from	flo^gg	to the top with the pyrite.

          ::;!~ :.:  •Humphrey Spiral.  A; shiny of coal and water is fed into the top of a spiral conduit. ^ The
   *™*** ™' :
                    flowing1 particles are' stratified by differences ...... in density, ....... with ..... the ..... denser ...... fractions ....... flowing .....
                           IS ...... fe ...... wal| ....... SlJhe ...... condjii|s ............... A ...... spIntiGratlSe ...... imm separates the stratified
                  5*sluny into final product and middlings.
; [[[ I ............................................... facilities.   '  '               •      "
                                                          ....... These ..... products ...... are' ..... fed ...... to separate dewatering
        •»•	*E!!tS	&*hTOcycJoiies.  A slurry of coal and water is subjected to centrifugal forces in an
                    ascending vortex. The denser refuse material forms a layer at the bottom of the vessel.
H&8HHi:!!li'riE!!SpfiS	Circulating'water skims the clean coal from the top of the stratified shiny and directs the"
^^^•;i^ ''^^,1 product to a vortex finder, which feeds the cyclone overflow into the product dewatering
•»^^^^^^^^^^^^^^^   	i»^^^       	"stage (Nunenkamp, 1976).  Feed coal sizes range between 0.044 and 64 mm (0.002	and	
           ill  "•"iiii	iii'ii'ijiiiii_ . *
                    25 in).

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EIA Guidelines for Mining
Overview of Mining and Beneficiation
]
.
,
Exhibit 3-31. Feed Characteristics of Unit Cleaning Operations
for Sizing and Separation of Crushed Coal
s > f "~
*• -,
Coal Cleaning Unit
isaumjig
Belknap washer
Chance cone
Concentrating table
DSM heavy media cyclone
.Flotation cell
Humphrey spiral
Hydroseparator
Hydrotator
Menziescone
Rheolaveur free discharge
Rheolaveur sealed
discharge
Water Required
per MT of Feed
ttpn)
12 to 21
21
29 to 50
50 to 67
83 to 125
(heavy media
slurry)
54 to 67
125
58 to 75
50 to 67
58 to 75
12 to 17
25 to 50
Maximum ••:••• ':• ••.':
• Feed -Rate--? --.^
(MTph)
9.8 to 48 per m2
of jig area
124
488 per m2 of
cone area
9.1 to 14
4.5 to 32
1.8 to 3.6
0.9 to 1.4
1.4 per vertical
cm of vessel
49 per m2 of "
surface
273
1.1 to 1.8 per cm
of vessel
2.9 to 3.6 per cm
' of vessel
Range of
Feed Sizes
(cm)1
0.3 to 20
0.6 to 15
0.2 to 20
0 to 0.6
0 to 0.6
0.030 to 0.0075
0.6 to 0.0075
1'.3 to 13
0 to 5.1
1.3 to 13
0 to 0.6
0.6 to 10
Percent Solids
in Feed
85to90
85 to 90
85 to 90
20 to 35
12 to 16
20 to 30
15 to 20
85 to 90
85 to 90
85 to 90
15 to 30
15 to 30
'Range of feed sizes is listed for bituminous coal only. Anthracite feeds for Menzies cones and
hydroseparators range between 0.08 and 13 cm. The DSM cyclone accepts anthracite feeds between 48
mesh and 0.75 in. The flotation cell accepts 200 to 28 mesh. The Belknap washer does not process
anthracite.
Source: Apian, F. F.. and R. Hogg, 1979. Characterization of Solid Constituents in Blackwater
Effluents From Coal Preparation Plants. Prepared for the EPA and U.S. DOE, EPA-600/7-79-006, FE-
9002-1, Washington, D.C., 203 p.

                                         3-141
                    September 1994

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    llllllllllllllllll
  l II" 111 111 1111 ill illiilli i  ^^ 111 lip lililillii III III npll lllllll   \^f ill III  	I"'	!	i	'	'	'	ii	|l1111	1	in	i	'	"'	I	i	i"	'	i	'	i	i*	|	


   I1    ,                         .   .  •                <                                    '
  verrieff; of Mining and BenefidatJon	                  EIA Guidelines for Mining

   ]	'	_	'	                                                            i	
                                  Exhibit 3-32.  Typical Circuit for Dense Media Coal Cleaning
                                                                                        PLAiiT  ALTERNATE!
 COARSE MAC. SEPAR.    CLEAN COAL
 FINE MAG. SEPAR.         A     •
 CENTRIFUGE          LOADING OR
 CENTRIFUGE          «*•« «*
 CENTRIFUGE
 CRUSHER
 CYCLONE
LIGHT MEDIA SUMP
HEAVY MEDIA SUMP
HEAVY MEDIA SUMP
                                                          SCREEN
                                                         SCREEN
                                                REF. RINSE SCREEN
TO REFUSE UN
                                                COAL RINSE SCREEN
                                               SLURRY SCREEN
                                                REFUSE RINSE SCREEN
                                               MVY. MEDIA RATH
                                               HVY. MEDIA CYCLONE
                                                            EMISSION POINTS
                                                        (1) TO WTER CLARIFICATION
        	Ill
III	IIIIIIIIIIM	Ill	lllllii  ! III H lllllllII) ill  illIill	llilllllll
                                               3-142
                                                  iiiiiir iii i
                                                                                                       September 1994
                                        • 11111 in 111111 iiiii in iiiiiiiiiiiiiiiiiiiiiiii i  in
                                                                 IIII    i III I" Hi III Illllllllll ill III 11 111 ill lllllll il IP 111 111 III 11 IIII III   III llilllllll ii 111 IIIIIIIIIIIIIIIH i illill III 11 ill IllIill lllllll
                                                                II llilllllll lllllll II II lllllll lllllll I III IIIIIIH^^  I llilllllll lllllll 11 Illllllllllllllll II llilllllll 111 III IIII llllllllllllllllll 111 111 Illllllllll II llllllllllllllllll    llilllllll 111 llllllllllllllll||l|
                                                                              i          I                              Ii	IL

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  EIA Guidelines for Mining	_	              Overview of Mining and Beneficiation


       •   Jiggings.  A shiny of eoal and water is stratified by pulsating fluid. Clean, low density
           coal is skimmed from the top of.the vessel.  The accuracy of separation is low. Sizes of
           feed coal range between 3.4 and 76 mm (0.1 and 3 in; Exhibit 3-33).
                                                                                               *.
       •   Launders.  Raw coal is fed with a steam of  water into the high end of a trough. The coal-
           water stream stratifies as it flows down the incline.  The denser refuse material forms the
           bed load of. the trough while the less dense coal is suspended in the stream.  The cleaned
           product is split from the stream at the low end of the trough. Feed coal sizes range
           between 4.76 and 76 mm (0.19 and 3 in).

       •   Pneumatic.  Streams of pulsating air stratify the feed coal across a table equipped with
           alternating decks and wells (Exhibit. 3-34), Refuse is pushed into the wells and withdrawn
           under the table.  The cleaned product rides over the refuse and is withdrawn at the  '
           discharge end of the table. Feed coal sizes range to a maximin^ of 9.5 mm (0 38 in-
           Exhibit 3-35).

       •    Wet tables.  A slurry of coal and water is  floated over a table that pulsates with a
           reciprocating motion.  Denser refuse materials flow toward the sides of the table, while the
           cleaned coal is skimmed from the center.  Feed coal sizes range between 0.15 and 6 4 mm
           (100 mesh and 0.25 in).


 The process waters used during the coal separation stage generally are maintain^ between pH 6.0
 and 7.5.  Waters with lower pH inhibit the flotation of both coal and ash-forming substances.  As pH
 increases, the percentage of floating coal maximizes,  but the percentage of floating  refuse also
 increases. The pH of process waters may be elevated with lime.  Reagents may be added to control
 the percentage of suspended fines (Zimmerman, 1968).


 Make-up water for cleaning plant operation ideally has a neutral pH, low conductivity, and low
 bicarbonate content.  The water preferably is free from contamination by sewage, organic material,
 and acid mine drainage. Other dissolved constituents also should occur in low concentrations (Exhibit
 3-36).                                                            •


Product dewatering (Stage 4 of Exhibit 3-24) includes the use of mechanical devises, thermal dryers,
and agglomeration processes to reduce the moisture contents of processed coal and refuse
(McCandless and  Shaver, 1978; Exhibit 3-37).  The moisture contents of products dried by typical
processes  appear in Exhibit 3-38.  Mechanical processes are of two general types:


      •  In-stream process that do not produce a final product (hydrocyclones.and static thickeners).
         These processes remove approximately 30 to 60 percent  of the moisture in feed material.
         Thickeners and cyclones usually are placed on line with other drying devices that reduce the
         moisture contents further.

      •  End-of-stream processes that produce a final product (screens, centrifuges, spiral classifiers
         and filters).                                                      «»    r             •
                                            3-143                             September 1994

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              Orel-view of Mining and Benefitiation
                                                                EIA Guidelines for Mining
IV
      Illlllllllllllli
illlillH
                                   Exhibit 3-33.  Typical Circuit for Jig Table Coal Cleaning
                    SCREEN
M
                                    REFUSE BIN    { )
                                (1) TO HATER CLARIFICATION


                                A POINTS OF EMISSION
                                                                 CLEAN-COAL LOADING
                                                                      OR STORAGE
               Source:  EPA.  1977.
             Ill 111 III            '  	I	Ill	I	in	Ill	  I	II	Ill	1	1	1	1 nil	

                                                              3-144                                 September 1994

IlllllllH I IIIIIIIIIIIII III III 111 I III III l||llllll Illlllllllllllli Illlillill      Illlllllllllllli  in! Ill II  Mi illlliiilililll I  Illlllllllllllli 111 hi Illlllllllllllli  111 111 IIIII 111 in I ll'l III IIIIIIIIIIIII I n'HI 111 ill  II 11 II Illlllllllllllli  ili|l|l|iil|i|||||||llillillill|llill Illllliill llillhli1 II	Ill

  I                I       	l	I	I	I	I	|li|	|	I	I	I	in	|	I	HI	I	I	Ill	I	

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 EIA Guidelines for Mining
Overview of Mining and Beneficiation
                  Exhibit 3-34. Typical Air Table for Pneumatic Coal Cleaning

                                                                      *

                                                                      •FEED BIN



                                                                     MOTOR

                                                                     SHAKER UNIT


                                                                      SPEED REDUCER
                                                                       I

                                                                       AIR DUCT
               CLEAN COAL
                                                                      DAMPER
                                         HUTCH
Several of the process that are used for Stage 3 separation also are used for Stage 4 dewatering,
including hydrocyclones, centrifuges, and spiral classifiers.  These processes are described above.
Static thickeners, screens, and filters may also  have a separation function; but are more appropriately
described as dewatering processes.


     •  Static thickeners generally are used in conjunction with flocculants to settle the fines from a
         static pool of preparation plant refuse water (blackwater). A typical thickener feed contains
         1 to 5 percent solids; thickened underflow contains 20 to 35 percent solids.  Common
         flocculants include inorganic electrolytes such as lime and alum, and organic polymers such
         as starches and polyacrylamide (Apian and Hogg, 1977).  Sludge from the thickener
         underflow may be dewatered further by mechanical devices, thermal drying, or
         agglomeration.  A typical  thickener vessel appears in Exhibit 3-39.

     •  Screens serve dual functions of dewatering and sizing.  The mode of operation (fixed or
         vibrating), mesh size, and bed depth of feed material are chosen on the basis of raw feed
         characteristics (gradation and moisture content), feed rates, and the desired efficiency of
         sizing and dewatering. The sieve bend, a typical dewatering and sizing screen, appears hi
         Exhibit 3-40 (Nunenkamp, 1976).

     •   Filters are of two types—pressure and vacuum.  Both types generally accept a feed with 30
         percent  solids at 27 dry MT (30 T) per hour.  Pressure filters produce a cake with 20 to 23
         percent  moisture. Product cake from vacuum filters may contain 34 to 40 percent moisture.
         The moisture removal efficiency of the pressure filter is offset by its higher capital cost
         relative to vacuum filter systems.  A typical vacuum filter appears in Exhibit 3-41
         (Nunenkamp, 1976).
                                            3-145
                    September 1994

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             	I	;	


                  t
                             of Mining and Benefitiation
                                                                                               EIA Guidelines for Mining
   l'«l	Ill	Ill	ill
    III III 11 in ill 1111  lllill1
    iii'iiii	ni	in
                                        Exhibit 3-35. • Typical Circuit for Pneumatic Coal Cleaning
                                2 X 3/8 •*•
                                                              TO LOADING  OR WET CLEANING
                                                                                                                           VENT TO

                                                                                                                           ATMOSPHERE
  in	if	i	i ill
                                         EMISSION  POINTS

                                         STACK EMISSIONS
                Source:  EPA.  1977.
lllllllNlllIil lllill ill  IP i  111111  II ill ill il "Illi ill i IH     	1111!  ill"!!' 1111 n'lil 1111 lull
                                                                         3-146
                                                                                                           September 1994
  IH^^^^     	Ill 11 IllB   	liillllBtmum lUllllil"'illllll	lliliiillillllll iiil'll  11II1 ilil	Nil	lull ill11	1.1  i	
•ilil in iiiiiiiiiiiiiiiiiiiiiii iiiiii 11 iiiiiiiiiiiiiiiiiii
                              liiillllllill                IIIIIIIII III  I IIIIIIIII I 111 II 111 111 I 111 II  II II  llllll|lllllll|llllllllllllllllll I Mil Illllll I  III IIIIIIIIIIIIIIIIIII
                                                                                     lllill  1  IIIIIIII  IIIIII 111  I liiillllllill III  111  111 liiillllllill I III III III III   liiillllllill   I   IIIIIIII  111 lllill II111111111 liiillllllill  I  I I Illi
                                                                                     iiiiiiiii iiiiiiii I mi  ill  I 1 liiillllllill I iiiiiiiii iiiiiiH^         in  liiillllllill iiiiiiii inn iiiiiiii 11 in 111(11 ill iiiiiiM     ii  nil lllill
                                                                                     liiillllllill lllllll  liiillllllill 111 liiillllllill IIIIIIIII IIIIIIIII IIIIII I|II|II11M   liiillllllill II IIIIIIIII^         II 111 Illlllllllllllllllllllllllllllll I lllll|lllll III IIIIII IIIIIIM      IIIIIIIII IIIIIIIII 111 I lllllllll|l lllllll(

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     Guidelines for Mining
Overview of Mining 'and Beneficiation
Exhibit 3-36. Desirable Chemical Characteristics of Make-Up Water for
Coal Cleaning Processes




,











f s-
. Parameter
pH
Hardness as CaCO3
Ca
•Mg
.Na
K
NH«
C03
HCO3
a
S04
N03
NOj
P04
SiO2
Concentration*

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                                                                    IIII 111 I III I I I
    Overview of Mining and Benefidation
                                                                  EIA Guidelines for Mining
ii in i

                                \im™i\ ii	iiiiilJi'iiimmiiii''in	8"!'ii "m ii iiB^^^^^^^^^^^^^^^^^^^^^^^	     '  iiiiiiiiii 1•!	!	I,
Exhibit
?8M X 6
SLURRY
3-37. Typical Product Dewatering Circuit for Coal Cleaning
. <8M X 0 REFUSF
. t- RAW COAL
I/CYCLONE
ts
OFAM
P_FFLOTATION CELLS
fnii

4S X
                RETURN TO
             WSH1NS CIRCUIT
          TO STREAM
                                          DISC FILTER
                                   CLE4H CQgL      CLARIPTED WATER
                                RETURN TO  THERMAL     RETURN TO
                                 DRYER OR LOADING       CIRCUIT
                                            3-148
                                                                          September 1994

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 EIA Guidelines for Mining
Overview of Mining and Beneficiation
I
Source:
First Ai
150,15
Ixhibft 3-38. Typical Moisture Contents of Dried Product from Selected Drying
Operations in Coal Cleaning Facilities
' , ,, ,,,, Typeof '
Equipment or Process
Dewaiering screens
Centrifuges
Filters
Hydraulic cyclones
Static thickeners
Thermal dryers
Oil agglomeration
Moisture Content of
Discharge Product (%)
8 to 20
10 to 20
20 to 50
40 to 60
60 to 70
6 to 7.5
8 to 12

McCandless, Lee C., and Robert B. Shaver. 1978. Assessment of Coal Cleaning Technology:
mual Report. EPA, Office of Research and Development, Washington, D.C., EPA-600/7-78-
3 p. ' •
      •  Multilouver dryers comprise two concentric, revolving cylindrical shells, each fitted with
      .  louvers that support the bed of feed coal and direct it toward the discharge point.
         Multilouver dryers can handle large volumes of wet material that require a relatively short
         drying time to minimise the potential for in-dryer combustion of the feed product.

      •  Rotary dryers consist of a solid outer cylinder and an inner shell of overlapping louvers that
         support and cascade the drying coal toward the discharge end.  Drying action can be direct
         (using the products of combustion), or indirect (using an intermediate fluid for heat transfer
         between the shells).

      •  Screen dryers apply gas pressure from combustion to squeeze the moisture mechanically
         from the feed coal through the supporting screens.  A lower percentage of coal fines
         (relative to other drying processes) thus may be lifted from the  bed.  Coal is exposed to
         drying heat for approximately SO seconds.

      •  Suspension or flash dryers continuously introduce feed coal into a column of high
         temperature gases (Exhibit 3-43).  Surface moisture is dried almost  instantaneously (flash
         dried).  Coal is exposed to the drying gases for approximately 5 seconds.

      •  Turbo-dryers contain an inert nitrogen atmosphere (less than 3 percent oxygen) that
         prevents the explosion or ignition of coal fines in die sealed drying compartment.  Wet coal
         enters a stack of rotating circular trays that successively feed the coal to lower trays using
         stationary wiper blades.


Indirect heat dryers use heat transfer agents (including oil, water, or steam) that do not come into
contact with the feed coal. Drying coal is circulated through the heating chamber on covered
conveyors that may be equipped with helical (worm) screws,  fines, paddles, or discs.  The drying
fluid circulates around the conveyor and through the hollow screws.
                                            3-149
                     September 1994

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        .   Orel-view of Mining and Beneficiation
                                                                     EIA Guidelines for Mining
i iiiiiiiiiiiiiiiiiiiii iiiiiiiiiiii
             Exhibit 3-39.  Thickener Vessel for Dewatering of Coal Cleaning Products
                 : NmrCTVamp, David C., 1976.
                                 operations (Stage 5 of Exhibit 3-24) are discussed more thoroughly in
              Eg*	ESS"?,**™18 document, The,	degree of sophistication in individual storage and loading
              *' "*•—*"Ms part me volume of coal being processed, stored, and shipped, as well as the lands
                            av5*flable-
                                                   systems can load a moving train directly from
                                                                    ...... lowers ....... and dump trucks to feed
3.5.2.2    Process Blow Sheet for Typical Operations

Thj complete-coal, cleaning plant utilizes a series of unit processes to prepare ROM coal for storage
           ":	2^2	P,!0^!5*!	BSst	be	mutually	compatible	for proper operation of the plant. Rates
                                  .^"M:5°!3Pj™5!?fto?capabilities of other in-line processes.
                               , especially in operations  that use heavy media such as magnetite
                           °°
               water
                                                   3-150                             September 1994

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EIA Guidelines for Mining
Overview of Mining and Beneficiation
     Exhibit 3-40. Schematic Profile of a Sieve Bend Used for Coal Sizing and Dewatering
                         FEED
                                                      SCREEN SURFACE


                                        OEWJTCTED
                                        mooucr
                                      3-151
                 September 1994

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                                                                                                                          Ill III 111
              Overview of Mining and Benefication
                                                                    EIA Guidelines for Mining
                                                              miillliiiiiiliii i I	in
III	•
IlllllH
                                    Exhibit 3-41.  Proffle View of a Coal Vacuum Filter
                                                                             DRYING ZONE
                             otsounci
                          SUIftMY FEED
                                 OtSCHAMC
                                                                                          SECTION
                                                                                        OVERFLOW
               Source:  Nunenkamp, David C.. 1976.

                                                                                                                   in n n in inn i i i nil i hi
ill mm'ii
III •ill i i1
iiii1 uiiiiiiiiiiiNiiii IIP
  l" HI	IIIHli1
    'iii (iinii II	i	in111 in iiiiiii|i)iiiiiiiiiii ill i in	in	Hi mi  i iiiiiiiiiiiiiiiiiii ii i iiiiiiiiiiiiiii
iiPi 11 in i	iimi'i luiiiii  hi	iiiiw   '
                                                                                      111 111        „	II	

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EIA Guidelines for Mining
Overview of Mining and Beneficiation
                                      3-153
                 September 1994

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Overview of
                                  i ..... i ......... Ill ........ II ..... lull .......... | ..................... I .................... I ...................... li nl ................ I .................... I ..... Ill ......... 1 ............. In ij ................... I .......... I ...... Ijillill ...... Ill ........ . ................................... |liiliiliii| ................ I ........ I .............. Iliilll [[[ I ............. I ........... lijj|| ............. 11 ..... II ...... . ...............



                         and Benefication _  EIA Guidelines for Mining
                                 Exhibit 3-43.  Typical Flash Dryer
(1 III III • i I ill
                   ALTERNATE
                  WET SCRUBBER.
                  (IF REQUIRED)
                                              '  C-E RAYMOND FLASH DRYING
                                                    SYSTEM FOR COAL
  	ilillll
         ALTERNATE ARRANGEMENT
        FOR VERY  FINE WET COAL
  •li ni in

  	i	
                                              VENT	^RELIEF VENT
                                                    **
                                      4IRY COAL
                                       CONVEYOR LJ,
            DRY COAL DISCHARGE
              FROM AIR  LOCK^.

                AUTOMATIC
                DRY  DIVIDER

               DRY RETURN

               WET FEED

               MIXER
-•-DRYING COLUMN


   DRY COAL CONVEYOR

   MET FEED CONVEYOR

   WET FEED BIN

   GATE

     T FEEDER
                                                                 DOUBLE FLAP VALVE

                                                            TEMPERING AIR DAMPER
                                                        ^^
                              	!	3-154
                                             •

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 EIA Guidelines for Mining	'      	Overview of Mining and Benefication

 slurries for the separation of product from refuse.  Evaporation and consumptive water use may
 require the introduction of make-up water to the process cycle.                                .

 A complete process flow sheet can be broken into three parts:

      •   Coarse stage (Exhibit 3-44)
      •   Fine stage (Exhibit.3-45)
      •   Sludgfr stage (Exhibit 3-46).

The coarse stage feed fine coal and refuse to the fine stage.  Coal slime, which includes fine coal and
refuse, is fed to the sludge stage.  Each stage .produces characteristic blackwater and refuse. Process
waters from the fine coal and sludge processing stages generally contain higher proportions of fines,
especially clay-size particles, than coarse stage process waters.  A series of thickeners, cyclones,
screens, filters, and dryers may be used to recover a iriaTimom percentage of solids from the recycled
process waters.
                                             3.155                              September 1994

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	Overview of Mining and Benefiriation
                            EIA Guidelines for Mining
infill H^  Ilillll I i ll|i|li||i|l
    Ilillll Ilillll Ilillll
    llWliillH III
IllllllllH IIIIIIIIM
                 Exhibit 3-44.  Coal Cleaning Plant flow Sheet for Coarse Stage Separation and
                                          Dewatering
            Row CotHi
^ Trash
                                              tr—--—..X^..—-
                                              •   FINE COAL   .
                                I- ;_.	,  j    PREPARATIONS
                                Orjm-Rm«*  |  j(S** Fif«r* 35 }i
          Source;  EPA. 1976.
                                            s  »••.•••—•••^.•^
                                            ]  f COAL"fiLli«l

                                           ti«
                                                            LEGEND
                                       mti^z
                     '• Rout* of Coors* Cool
                           of Refus*
                      Rout* of Heavy Media Slurry
                     •Optional Route-Snk-F!oat*Msaia
                     -Route of Sink-Float-f M*4ia
                     •Route of Mogiwtit*
                      Route of Dirty Process Water
                      Route of Clean Process Water
                      Route of Fresh Mofafup Water

                                           5-156
            I	
                                   September 1994

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EIA Guidelines for Mining
                 Overview of Mining and Beneflciation
   Exhibit 3-45.  Coil Cleaning Rant Flow Sheet for Fine Stage Separation and Dewatering\
                                       . _
              (SooFigur* 34)   «•«•••«
               ,    fc   , _ . .	       •. » «»
              Mokt-ap
               Wfltof
              Storooo
                             I Medium T
         to R«f UM
          Disposal
                                                          To-Dttliming Screen
                                                            (S«« Fiur* 34 )
   ie Stporoter
   i^m^mft^m


LEGEND

          N
           MIM» Opfionof Routt of Fino Cool
  —fr-Rauta of Sink*FIoot
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   ^^^     111 111 11111 111 I 111 Illlllllin        Illlllllf II
                                            111 111 111 11(111111 111 111
                                     in iiiii  iiiiiiiiiiiiik  i in in i  i
                                                          111 III III 111 1111 111 1111I111 llilllllllilll
                                                                .      iiiiiiiiii iiiiiiiiiii in 11 in
iiiiiiiiiiii iiiiii iiiiiiiiiiiiliill
1H^
 MI 11 iiiiiiii i iiii in in i in iiiii in iiiiiiiiii
                    of Mining and Benefication
                                                                                 EIA Guidelines for Mining
                                                        iii 11111111 iiiiii nil MI iiiiii iiiii iiii 11 ill n in livlliiilililnnlnininiy   iiii n i nun n i  in in ill in
                 Exhibit 3-46.  Coal Cleaning Plant Flow Sheet for Sludge (Slime) Separation and
                                                    Dewatering                     *~
                 Ced Sliffx Frmn Dtstifnitu
                         Hydfo-Cydenji
                                                 *....,..
                                                                                fttflltt
                                                                               »i*pe«ol
                                               LEGEND
i	Ill
                     -Route of Cool
                                                                  -ROU!« of Coktd Rtfust
                                            «*-Rout» of R.fon
       Source:  EPA. 1976
  111 III !•	IIIIII	IN|III111H  	IIIIII	iV    	IIIII	(Ill
                                    n nil
                                                  3-158
                                                                                       September 1994

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  EIA Guidelines for Mining  	                    Environmental Issues


                             4.  ENVIRONMENTAL ISSUES

 This section describes the environmental impacts associated with new source mining operations. The
 mining industry and its potential environmental impacts are unusual in a number of ways, of which
 three may be the most important.  First, many of the potential impacts are unique to the industry
 (acid rock drainage, releases from cyanide leaching units, structural failure, etc.).  Second, many of
 the impacts may be those manifested years or decades after mining ends and can intensify over time.
 Finally, the nature and extent of impacts from mining operations, perhaps more than any other
 industrial category, are based on factors that are specific to the location (including geology,
 hydrogeology, climate, human and wildlife populations, etc.).  Impacts from similar types of
 operations can range from minimal to extensive depending on local conditions.  These factors
 emphasize the need for full understanding of baseline conditions and careful planning to avoid/
 mitigate potential impacts.

 As in all major industrial operations, careful design and planning play a critical role in reducing or
 mitigating potential impacts. In the case of the mining industry, the three characteristics that
 distinguish it from other industries (unique impacts, often delayed, that depend on site-specific
 factors) make initial design and planning even more crucial. This in turn makes any assessment of
 potential impacts, both immediate and long-term, reliant on detailed information on site-specific
 conditions, and on the design and operation of the facility.  Site-specific information is generally
 incomplete at the time of permitting. Design and operation plans, including operations to mitigate
potential environmental impacts, are often only conceptual at the time of permitting. This makes it
extremely difficult to delineate the types of information and analyses that are necessary to assess
potential impacts.

The following subsections are organized according to  the major environmental issues that are raised
by mining operations. These include:

      •   Acid rock drainage
      •   Cyanide
      •   Structural stability of tailings impoundments
      •   Natural resources and land uses
      •   Sedimentation/erosion
      •   Metals and dissolved pollutants
      •   Air quality
      •   Subsidence
      •   -Methane releases from coal mining and preparation.
                                             4-1                              September 1994

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                             ,                                                           I                        I         I
  lllllll I Illlllllllll III Illllllllllllllllllllllllll 11II 111 III II l|llin        IlililH^ IIIIIIIH^  Illlllllllllllllllllll I Illllllllllllllllll HI IIIIIIH lllllll I I 111 III11 11 111 III I Illlllllllllllllll II 11111 111 Illlllllllll II Illlllllll I 111 1|1 111 Hill III IIIIIIIIH III llllllllllllllllllll|llllllllllllll III1IIIIII11I1I1 I 111 Illlllllllllllllllll II III llll|llllll|lll|l llllllllllH     llllllllllllllll lllllllllll|lll|(
                     _
  Illlllllllllllllll Illlllllllll I Illlllllllllllllll Mill 111 l|lliilllilliiiiB                   Illlllllll  Illlllllll  ill   111 HIM I Mill I •                              l||         II       11          I
      4       Environmental Issues	       EIA Guidelines for Mining
             The discussion of each, of these subjects includes a description of the topic and of the types of
             information that are necessary to determine potential impacts.
             4.1    ACID ROCK DRAINAGE
            The	formation	of acid drainage and the contaminants associated with it has been described as the
           	Srgest environmental problem fiicing'the U.S. mining industry (U.S. Forest Service^ 1993; Ferguson
                               -Lakto,199
            mine drainage (AMD), acid drainage from mine waste rock, tailings, and mine structures such as pits
            and	underground	workings is primarily a function of the mineralogy of the rock material and the
                       of ^gj. and oxygen. While acid may be neutralized by the receiving water, dissolved
            metals can remain in solution.  Dissolved metals in acid drainage may include the full suite of heavy
           ===j!	'	=	i	|	   i    ,          '          i  "           "I ,  ',"   J  	        I,     1,1        *
           ilSHSS*	including lead, copper, silver, manganese, cadrnintnt fron, and zinc.  Elevated concentrations
                     in surface water and	groundwater	can	preclude then- use as drinking water supplies.
            Further,	low pH	levels	and high metals concentrations can have acute and chronic effects' on aquatic
            AcM drainage from coal and mineral mining operations is a difficult-and costly problem. In the
	United	IMS8, more than 7,000 kilometers of streams are affected by acid drainage from

                       et al.,1982).  Similar impacts are observed in coal mining areas of the Midwest.  As one
   ii^=Min|ny.	examples of historic coal mining areas, 2,400 acres of abandoned surface mine land
           northwest of Montrose, Missouri, are impacted by acid mine drainage. More than half of the 100
                                       less than 4 and there are 1,200 acres of "barren, acidic spoil."  Overland
                       mine spoil has pH values between 2.9 and 3.5 (Blevins, 1990).  In the western United
                  Jhe=	|?pjej|	Series jstmratesjbjt	between 20,000 and 50,000 mines are currently generating
                          Se^ce jandSi and that drainage from these mines is impacting between 8,000 and
                                       (U.S. Forest Service, 1993).
                                                                                I        i
                	
      generation prediction tests are increasingly relied upon to assess the long-term potential of a
      iii!g!!iiiii!!!!«!!!!!!!!!!!!!!S                                  i  Y inn in  i    	 *•*      r
         g,|	lg|te	g	generate	acid.	Becausennmeralggy_ and other factors affecting the potential for
      formation are highly variable from site to site, predicting the potential for ARD is currently
difficult, costly, and of questionable reliability.  Further, concern has developed because of the lag
.tifn^at	existing	mines	between	waste	emplacement and observation of an acid drainage problem
(Uniyersity of Caltfornia, Berkeley, 1988).  With acid generation, there is no general method to
predict its long-term duration (in some cases necessitating perpetual care).  The issue of long-term or
perpetual care of acid drainage at historic mines and  some active mines has focused attention on the
need for improving prediction methods and for early assessment of the potential during the
                                           U.S. Forest Service sees the absence
•MH||mKnMV2iiI	SS2S	jf,	££	22S	S&fliSHSfS ventures, as a major problem facing the future of
SS        meal mining in the western United States (U.S. Forest Service, 1993).
                               I
                                                      ii inn
                                                         4-2                               September 1994

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  EiA. Guidelines for Mining _                        Environmental Issues

  The problems presented by acid drainage are encountered worldwide, and there is a growing body of
  literature that documents examinations of all aspects of the phenomenon, from the genesis of acid
  drainage to prediction of the timing of its occurrence to prevention. The most recent advances in the
  field are compiled in the proceedings of the International Land Reclamation and Mine Drainage
  Conference and Third International Conference on the Abatement of Mine Drainage, which was held
  in April 1994 (U.S. Bureau of Mines 1994).
                                                        /

 The remainder of this section addresses the major topics related to understanding how acid rock
 drainage is generated, how to predict it during mine planning, how to detect it during operations, and
 approaches to mitigating its impacts.                    " .  •    ,

 4.1.1    NATURE OF Aero ROCK DRAINAGE               .

 4.1.1.1   Add Rock Drainage/Oxidation of Metal Sulfides

 Acid is generated at mine sites when metal sulfide minerals are oxidized.  Metal sulfide minerals are
 common constituents in the host rock associated with metal mining activity.  Prior to mining,
 oxidation of these minerals and the formation of sulfuric acid is a function of natural weathering
 processes. The oxidation of undisturbed ore bodies followed by release of acid and mobilization of
 metals  is slow. Natural discharge from such deposits poses little threat to receiving aquatic
 ecosystems except hi rare instances.  Mining and benefieiation operations greatly increase the rate of
 these same chemical reactions by removing large volumes of sulfide rock material and exposing
 increased surface area to air and water.  Materials/wastes that have the potential to generate acid as a
 result of metal mining activity include mined material such as spent ore from heap and dump leach
 operations, tailings, and waste rock units, including overburden material.  Equally or more important
 at some mines are the pit walls in the case of surface mining operations, and the underground
 workings associated with underground mines. .

 The oxidation of sulfide minerals consists of several reactions. Each sulfide mineral has a different
 oxidation rate. For example, marcasite and framboidal pyrite will oxidize quickly while crystalline
 pyrite will oxidize slowly.  For discussion purposes, the oxidation of pyrite (FeSj) will be examined
 (Manahan, 1991):

                                 2H2O +  TOj -> 4H+ + 4SO?
In this step, Sf~ is oxidized to form hydrogen ions and sulfate, the dissociation products of sulfuric
acid hi solution. Soluble Fe2* is also free to react further.  Oxidation of the ferrous ion to ferric ion
occurs more slowly at lower pH values:

                            4F62-1- + O2 + 4H* -> 4FC3* + 2H2O
                                             4-3                               September 1994

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	:	v	g^°n*ental Issues	;	'.	:	;		EIA Guidelines for Miniiig
                        mSmm ...... nw ...... mt ..... •iSi,,,,2«?xidation fa caXalyzed by a variety of Metallogenium, a •
            naturally occurring filamentous bacterium. Below a pH of 3.5 the same reaction is catalyzed by the
            naturally occurring iron bacterium ThiobadUasferrooxidans. If the ferric ion is formed in contact
            with pyrite the foljgwing  reaction can occur, dissolving the pyrite:
                                "'      '
                                        4-  14Fe?* + 8H2O ->  ISFe2* + :2SOf + 16H
          ,    f             .....  . • ,li  ;               .          .             ,•,,'.      .    '    '
           This reaction generates more acid.  The dissolution of pyrite by ferric iron (Fe3*), in conjunction with
           the oxidation of the ferrous ion constitutes a cycle of dissolution of pyrite. Ferric iron precipitates as
           hydrated iron oxide as indicated in the following reaction:
                                                                         3H
          Ill 1111 111 IIIIIIII 111  IlllllH        llllllH        IIIIIIII lllllllllllIB lllllin^                                          	
           Fc(OH)3 precipitates and is identifiable as the deposit of amorphous, yellow, orange, or red deposit
           on stream bottoms ("yellow boy").
                   1              i                                •  .  '   .                    ,  •',„,'„„'	'._,,' _' "„„',,"	j1  ,r	'",„,'	
           4.1.1.2     Source of Acid and Contributing Factors
          The potential for a mine or its associated waste to g_ enerate _acjd and .release ...... contaminants, ,|s, dependent
          OI       fectors and is site-specific.  Ferguso^and ...... Ericfaon ..... (1988) ....... identified primary, secondary,
                        tors ftat control acid jdiainage:" These factors provide a convenient structure for
                        discussion of acid formation in the mining envhx)nment. Primary factors involve
          production of the acid, such as the oxidation; jgacjions. Secondary factors act to control the products
          of the oxidation reaction, such as reactions with ..... ofhvjnfaaab ....... thM^consumelacid,,:  Secondary factors •
                              acid or react wiui other minerals, thereby releasing contaminants.  Tertiary
                ...... *£%* to ** Physical aspects of the structure or waste management unit (e.g., pit walls, waste
          rock piles, or tailings impoundments) that influence the oxidation reaction, migration of the acid, and
          consumption.  Other downstream factors change the character of the drainage by chemical reaction .or
          dilution.       •         •
K™SfSJ2 ...... S±5 ...... !,SJ! ......         .....       .....      .....         water, oxygen, ferric iron, bacteria to
................................................ " .................................. Jf^Jyze ..... the ...... oxidation i|reaction,| ....... and ..... generated ...... heat. ............... Some ....... sujfide ...... mjnerals. ....... are ...... rnorgiiisasi|ly oxidized
«ZI«^.g., ..... fean^dal ...... pyrite, marcasite, ....... and ..... pynirotite) ...... and ..... hence, ...... mayjiaye ...... a greater impact on tuning '
             ™_.__              .....        ....... _____ .....    ..... _ ........
                                                                                     Also, important is the
                                                                                     w|| ..... ,have ....... smallec
     •••!• ' |l||il||i||||||i|IHIII 'f Ilillllllllllliiliiiiiiiiiii  iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii inn iiiiiiiiiiiiiiiiii PI i' miiiiiiiiiiiiiiiiiiiiiiiin 11111111 in iiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii"! ii mi i  i iiiiiiii inn i iiiiiii n i n jiiiiiii in n~i	
     • exposed surface areas than those that are disseminated
     IIIIIH^    •Illllilll IIIIIIIH^^^^^                       	       -—.•••••.i»«^j.
         Both water and oxygen are necessary to generate acid drainage. Water serves as both.a reactant and a
         rGedhmi for bacteria in the oxidation process.  Water also transports the oxidation products.  A ready
                of atmospheric oxygen is required to drive the oxidation reaction. Oxygen is particularly
                                                      '                                '
                                                       4-4                               September 1994

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.  EIA Guidelines for Mining                                                Environmental Issues

  important to maintain the rapid bacterially catalyzed'oxidation at pH values below 3.5.  Oxidation of
  sulfides is significantly reduced when the concentration of oxygen in the pore spaces of mining waste
  units is less than 1 or 2 percent. Different bacteria are better suited to different pH levels and other
.  edaphic factors, (edaphic factors pertain to the chemical and physical characteristics of the soil and
  water environments).  The type of bacteria and.their population sizes change as their growth
  conditions are optimized (Ferguson and Erickson, 1988).

 The oxidation reaction is exothermic, with the potential to generate a large amount of heat, and
 therefore thermal gradients form within the waste unit.  Heat from the reaction is dissipated by
 thermal conduction or convection. Research by Lu and Zhang (undated) on waste rock using stability
 analysis indicates that convective flow can occur because of the high porosity of the material.
 Convection cells formed in waste rock would draw in atmospheric air and continue to drive the
oxidation reaction. Convection gas .flow due to oxidation of sulfide minerals depends on the
maximum temperature in the waste rock.  The maximum temperature depends on ambient
atmospheric temperature, strength of the heat source, and the nature of the upper Txmndary.  If the
sulfide waste is concentrated hi one area, as is the case with encapsulation, the heat source may be
very strong. Lower ambient air temperatures improve conditions for convective  gas flow. If the
upper boundary is'covered, convection is less likely.         .

Secondary factors act to either neutralize the acid produced by oxidation of sulfides or to change the  .
effluent character by adding metals ions mobilized by residual acid.  Neutralization of acid by the
alkalinity released when acid reacts with carbonate minerals is an important means of moderating acid
production.   The most common neutralizing minerals are calcite and dolomite. Products from the
oxidation reaction (hydrogen ions, metal ions, etc.) may also react with other non-neutralizing
constituents. Possible reactions include ion exchange on clay particles, gypsum precipitation, and
dissolution of otherminerals.  Dissolution of other minerals contributes to the contaminant load in the
acid drainage.  Examples of metals occurring in the dissolved form include aluminum, manganese,
copper, lead, zinc, and others (Ferguson and Erickson, 1988).

Some of the tertiary factors affecting acid drainage are the physical characteristics of the waste or
structure, how acid-generating and acid-neutralizing wastes are placed in the waste unit, and the
hydrologic regime in the vicinity. The physical nature of the waste, such as particle size,
permeability, and physical weathering characteristics, is important to the acid generation potential.
Particle size is a fundamental concern since it affects the surface area exposed to weathering and
oxidation. Surface area is inversely proportional to particle size. Very coarse gram material, as is
found in waste rock dumps, exposes less surface area but may allow ah- and water to penetrate deeper
into the unit, exposing more material to oxidation and ultimately producing more acid. Air
circulation hi coarse material is aided by wind, changes in barometric pressure, and possibly
convective gas flow caused by heat generated by the oxidation reaction.  In contrast, fine-gram
                                              4-5                               September 1994

-------
      •lllllllllill Illl
                	I	                          I	'	II	1	1	1	11	
                	"	'	""	[	I	I	l'"1	'	'	'	"I	'	''"
                 IIIIIIIII illllll lllllllllill IIIIIIIIIIIIIIIIM 1IIIIIIH n lllllllllill ill l||lllil|||i 111 . 	
                 Ill           '     .'	            •	h|       |             	!	
!jl!||!!L   	Ill	i|il||l||l| 	                                                     |      	i||(
                                                                             nil •• i in i iii|i inn 11 nn |i in ii i nn nn Hill i ii 111 ill i ii ii 111 in ii mil n n i nn n n in n nil n in 111 iiiiiiiii i in nn n in iiiiiiiiiiiiiiiiiiiiii|iiii i in Hill inn n  i nn i ii|iln i nn
             Enrironmental Issues	       EIA Guidelines for Mining
             material (e.g., tailings) may retard air and very fine material may limit water flow; however, finer
             grams exp^e more surface area to oxidation. The relationships between particle size, surface area,
             and oxidation play a prominent role in acid prediction methods and in mining waste management
             units. As waste material weathers with time, particle size is reduced, exposing more surface area and
             changing physical characteristics of the waste unit.  Though difficult to weigh, each of these factors
             influences the potential for acid generation and are therefore important considerations for long term
             waste management (Ferguson and Erickson, 1988; Lu and Zhang, undated).
                	-	",	I	!	Ii	'	;	•''	'	!  '    -     	'	
                I   I "            I	   J                  I          I     	       ,  A    I
             The hydrology of the area surrounding mine workings and waste units is important in the analysis of
             acid generation potential. When acid generating material occurs below the water table, the slow
             diffusion of oxygen in water retards acid production. This is reflected in the portion of pits or
            underground workings located below the water table.  Where mine walls and underground workings
            extend above the water table, the flow of water and oxygen in joints may be a source of acid. A
            similar relationship is evident with tailings, which, are typically fine grained and disposed of
            subaqueously; the slow diflusion of oxygen inhibits  formation of acid. However, since tailings are
            limited period of time during mine, operation. Following mine closure, the free water surface hi the
            impoundment may be drawn down substantially, favoring ARD conditions.  (Also, as tailings dry
            ove| Imae, previously impermeable layers of fine material may develop cracks or fissures, providing a
    ,'I1  	   	tjfi           -  ..     '               	in in	     ,	ii	if 'iiiii	iiiiiii in iiii' mum ill! i	iiiii mm	i	n"	in i ii	• i	i< iinn i	iiiiiii i	i	i, 11	n
    iiiiiiiiinifiiiiriii ii in i iiin^^                                            	iiLiiiiiii \< •     : »	•	'	
                spatial distribution of mining wastes in units, or waste placement, affects acid generation
	i	potential.  For example, the distribution of acid generating wastes'with neutralizing wastes may be
               |™J|!	    *   	!""'{l"""	,T|T"!'I	II	!!!!	*	'"I	"!"""!	"	!	'•	!	!	"""i""1!!!1 " ' • '• -" i'    •   •'"!'    ...    ''        r*       ' • " ,
'•^  idling SS^SS^^)^	2E	stggfrinj*	sequence^	^Calcareous^ material may be mixed with or placed above sulfidic
           wastes to buffer acid production or provide alkaliniry to infiltrating solution prior to contact with acid
           generating wastes.  An. alternative to layering or mixing is encapsulation. This technique attempts to
           isolater,,acid generating wastes from oxygen and water, thereby reducing its gotential to Pfoduce acid.
           Both tfiese	tediniques are curreniy being used in waste rock dumps.  It is unclear if they are effective
           over the long-term, since highly acidic material may overwhelm the buffering capacity of calcareous
           material or other alkaline sources.    ,   _       	;	
                i          ,  ii   i  i   	              .
                I            i                                                            !
           Wetting and drying cycles in any of the mine workings or other waste management units will affect
           the character of any acid drainage produced. Frequent wetting will tend to generate a more constant
           Volume of acid and other contaminants as water moves through and flushes oxidation products out of
           the system.	The _build-up_	°f f^njaminants	m	the	system is proportional to the length of time between
  1         wett|l prcies (Ferguson and Erickson,. 1988; Doepker,  1993).  As the length of the dry cycle
	!	""lincr^5S8	SiMllSS Pjrcxfacts will tend to accumulate in the system. A high magnitude wetting event
           will then flush accumulated contaminant^ out of the system.  This relationship is typical of the
                                 '              i                                         II      '
                                                                                        i
                                                                                        t

                                             •
                                                         4-6                              September 1994
                    in iiiiiiiiiiiiiiii IIIIIH^          111 mi iiii iiiiiiH^  nil ii iiiii iiiiiii iin  in iiiiiiiiii ill i in iiiiiiiiiiiiii i iiiiiiiii i  iiiiiiiiiiii i ill  iiiiiii n
                  "I	|	|	II	Ill	I	I	I	Ill	Ill	I	I	   	I	I	I	Ill	II	1	1	1	1	1	1	11"

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 ElA. Guidelines for Mining                              .                 Environmental Issues

 increase in contaminant load observed following heavy precipitation for those areas having a wet
 season.

 4.1.2    ACID GENERATION PREDICTION

 The objectives of predictive testing are to (1) determine if a discrete volume of mining waste will
 generate acid, .and (2) predict the quality of the drainage based on the rate of acid formation measured
 (California Mining Association, 1991).  There are two important points that must be considered when
 evaluating the acid generation potential of a rock material. The  first is how to collect samples from
 the field for use in analytical testing. The second is which analytic test method should be used.  Both
 points have a profound impact on the reliability  of analytical tests.  Results from any analytical test
 are only as reliable as the samples used for the test.  Once the sampling strategy is selected, an
 appropriate analytical method or methods can be selected. Methods used to predict the acid
 generation potential are classified as either static or kinetic.  Factors affecting the selection of
 sampling regime and analytical method include an existing knowledge of the geology,  costs, and
 length of time available to conduct the test.  This section will examine sample methodology and
 analytic tests used to predict acid generation potential.

 The following list of components describes the solid phase composition and reaction environment,of
 sulfide minerals.  Potential contaminants are included to indicate their importance in the scope of acid
 generation.  These components should be kept in mind while evaluating information on acid
•generation potential.          .                   •'

 Components affecting the total capacity to generate acid are characterized by:

      •   Amount  of acid generating (sulfide) minerals present (assuming total reaction of
          sulfide minerals)

      •   Amount of acid neutralizing minerals present

      •   Amount  and type of potential contaminants present.

 Components affecting the rate of acid generation include:

      •   Type of sulfide mineral present (including crystal form)

      •   Type of carbonate mineral present (and other neutralizing minerals, as appropriate)

      •   Mineral surface area available for reaction

              Occurrence of the mineral grams hi the waste (i.e., included, liberated)
              Particle size of the waste
                                               4.7                              September 1994

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                                                                          EIA Guidelines for Mining
            *   Available water and oxygen
     ';	in^^	•
    ^^
Bacteria.
                         1                    '
                     used to assess a material's acid generation potential are either static or kinetic in
                          determines both the,	tgtal,	acid-generating and total acid-neutralizing potential of a
                   capacity of the sample to generate acidic drainage is calculated as either the difference
                   QZ	as	a ratio of the values..	Tjiese tests	are	not	Intended	to predict the rate of acid
                        ; potential to produce acid.  Static tests can be conducted quickly and are
      inexpensive compared to kinetic tests. Kinetic tests are intended to mimic the processes found in the
                                   ' at an accelerated rate. These tests require more time and are
    	considerab.ly_inote	.expensive than static tots. Data from the tests are used to classify, wastes.
           Sg	to	their add generating potential,  fhls^mformation can be collected and evaluated during"'
                                                   ^
        $ ...... sconojnie ...... analysis ....... of mines. ....... in their exploratory phases.  Based on this information, management
    Zdecjsions can be made with respect to specific mitigation practices.
         I '••     ;• "     '".'.   .•  •      •                      ,      .    .M .   '      : '
       *  1   .......................... ; ......... ; [[[ [[[ ;; [[[ ; ........................ ;,                    .............. ; ......... : .............. ; ........................................ ; ............................. ; ......... ; [[[ I .......... ; [[[ ; ...........................................
      ESprts ..... tyboflnjK ..... mining ....... industry ...... and ....... S^^egulatory ...... agencies ...... to ....... devdogthe ..... best protocols for
                      —— —  — —     _     _           potentjaj j^^ Demonstrated that site-
     specific conditions (e,g., climate and geology) dictate a case-by-case approach when evaluating acid
     F^B^" ........... |TMS| ...... is ....... co^licated ..... by the fact that ..... a ..... variety ...... ofresearch ...... effom ....... on ...... different ...... methods, by
     the JBureau..^ MSie$^ EPA, and iie Canadian MJne E^^onment Neutral' Drainage (MEND), as well
     as those used by minmg companies and then: consultants, make comparison of data difficult.  Several
     researchers have conducted comparative evaluations of predictive tests (Lapakko, 1992; Bradham and
     CaswxJo, 1990; Coastech, 1989). Lapakko, of the Minnesota Department of Natural Resources, has
     conf uct«l ajroparative evaluations of static and kinetic test methods using a range of rock types.
     Bradham ....... and ...... Caruccio ...... conducted ..... a comparative study on tailings.
     When evaluating the acid generation potential of a waste, a phased testing plan selects samples
     appropriate for the detail needed (CaUfornia Mining Association, 1991).  This approach allows
     investment in acid prediction testing to be commensurate with a deposit's economic potential and
    'associated with unnecessary tests.  Sampling and testing should be an iterative
                               nd evaluating a small amount  of information to establish the acid
                         S™	S	S£	SSSS^ *>*<&*&> subsequent sampling and testing can be
    •'selected to refine .the information as needed.
         I"   _   i                     i               i                    i i        '

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  EIA Guidelines for Mining   .                    *                        Environmental Issues

       1.  Define the geologic (or litfaologic) units that will be encountered during mining.  Describe
           the geology and mineralogy of these units in detail..

      2.  Develop a sampling plan based on understanding of geology (rock mass, etc.). Collect
           samples to represent ranges of compositional variation within a rock unit (see Lapakko,
           1988, 1990a).

      3.   Select static or kinetic tests and evaluate potential for acid formation.

      4.   Evaluate sampling criteria and conduct additional kinetic tests as required.

      5.   Develop a model as appropriate.

      6.   Based on findings, classify geologic (lithologic) units as acid, non-acid forming, or
           uncertain.  (Note: the potential to produce acid may vary within a given geologic unit.)

 4.1.2.1     Sampling

 Selection of samples has important implications for subsequent acid prediction.  The purpose of
 testing rock material is to allow classification and planning for waste disposal based on the predicted
 drainage quality from that material.  Samples must be selected to characterize both the type  and
 volume of rock materials and also account for the variability of materials that will be exposed during
 mining.  When to collect samples for testing is an equally important consideration.

 Researchers agree that sampling and testing should be concurrent with resource evaluation and mine
 planning (Lapakko, 1990a; British Columbia AMD Task Force, 1989). Sampling techniques used to
 evaluate recoverable mineral resources (assay samples) are similar to those required for prediction of
 acid generation potential.  Active mining operations for which predictive tests were not conducted in
 advance of mining lack the advantage of front end planning, but can still use sampling and other site-
 specific information (e.g., geology and mineralogy) to establish the acid generating potential.

 The pressure is increasing for new operations or those in the exploratory phase to accurately predict
 future drainage water quality.  By comparison, the acid drainage potential at old mines may  be well
 established. Examples of information needed from existing operations are the quantity of existing
 acid products; the potential and stage of acid generation in each of the waste units, and the acid
forming potential of future wastes to be generated. Broughton and Robertson recommend that the
first two stages of an acid prediction analysis for either new or existing mines  are (1) to review .the
geology and mineralogy and (2) classify the rock and collect samples (Robertson and Broughton,
undated; Broughton and Robertson, 1992).

 Sample collection for prediction tests for both old  and new mines should consider both geologic and
 environmental factors. Geologic factors for sample selection are primarily a good understanding of
the local geology.  If available, this may include information from mines, core logs, or other sources


                                             4-9                               September 1994

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                                                                                 EIA	Guidelines	for	Mining
            in the immediate area. This information is important to both the sampling program and application of
            test results. Environmental factors include consideration of the potential environmental contaminants
            in	tne	rocjc	and	climatic variables.	A	quality assurance/quality control program should be developed
            and coordinated	with	the	mine plan for sample collection and acid generation testing.
            1	i	'	'	'""	'	!	,	;	!	;	:	"	"	I	
            There are many opimons concerning the number of san^Ies to be collected in a fixed-frequency
            sampling	program.	One	mining consulting	firm	recommends	about	8	-	12	samples of each significant.
                 type or a minjmum of one sample for each one million tons (Schafer, 1993).  In this case a
            significant rock type	represents one or two percent of the total mine rock volume. ^ A representative
            of the U.S. Forest Service suggests'that one sample (about 1,500 grams) be collected per 20,000 tons
           of waste rock, or about 50 samples for each one million tons (U.S. Forest Service, 1992).  These
                        ":" 	I	fciL:	-si	Pllli	||	!	!;:	!	T	'•	»4i	a	I	'•	»	Iiii	-•
                   would be coUected oy compositing cuttings from individual drill holes made prior to blasting.
           The British Columbia AMD Task Force recommends a minimum number of samples based on the
 	"	sj	I	'	'	!	'	'	ijij	"	'"'"""'!'"'"""	J|	'"	'"""	!	'	'	I	""	'	!	|	'	|	I	'	"	'	  i,
       ,    mass of the geologic unit.  Their recommended minimum sample number is 25 for a one million ton
           geologic unit, or one sample for every 40,000 tons. Using the British Columbia method, as waste
           volume increases, the proportional number of samples decreases.  For example, for a unit of 10
           million .fogs, the minimum sample number is 80, or one sample for every 125,000 tons (British
           Columbia AMD task Force,  1989).

           There are reservations to prescribing a number of samples for collection per volume of material..
           This is particularly true for existing mines when collecting samples from waste rock dumps for acid
           generation potential tests.- -Waste rock .dumps are usually constructed by endkiumping rock from
           trucks, creating heterogeneous deposits that are very difficult to sample with confidence. Tailings are
         .  comparatively more uniform due to milling and depositional methods used, and it is easier to charac-
           terize their variability.  Fixed-frequency sampling does not rely on the use of best judgment on the
           part of tie sample collector (typically a mining company).  It also does hot provide the statistical basis
           to account for variability among samples.  Therefore, the actual numbers of samples to be collected
           should be determined on a site-specific basis.                                                '  .
                            ii                           '  , •        '       11       ' i                i'
                                                                                  •
                                1                                      *                  '            .
           Factors to consider in a sampling program for existing or planned mines include the method of
           •iiiii i"	1	a	'	t	•                                                          • • • -.
           sample collection, length of tone samples are-to be (or have been) stored, and the sample storage
           environment. Each of these can affect the physical and chemical characteristics of a sample.  Samples
           collected from cores exposed to the environment may be physically and/or chemically altered. If
           samples are collected from a drill core, contamination may be a problem if a lubricant was -used.  At
           existing mines, tailings samples should be taken over a variety of depths  to determine if oxidation of
           sulfid minerals is occurring.  The influence of lime addition during milling may  maintain alkaline
                      Collecting samples of waste rock is difficult because of the variability inherent in these
          waste units.  Drilling is considered to be the preferred method for collecting samples from waste rock
    iiSSwiHi dumps (Ferguson and Morin, 1991).
    ill	miim IIH^	IH	IPIllll"	lilINliilllilill'llilllllllli11 I	li'l Illillii II	ll'llillllllll''!!!!'!'!	'                   	!H
IIIII 111 IIIIIIIH^    I IIIII III 11II IIII  III Mill llllllllllllllllll|llllllll I II ill III I IIIII IIII I Illllllllllllllllll II  IIIIIIIB^   11111 IIIIIIIII IIIII III I IIII IIIIIIIII III 11 II  III IIIII  II II IIIIIIIII IIIIIIIII 11II11 III IIIII  III 111 IIIII  IIII ill III IIII  I I III 111 IIII IIIIIIIII I 111111 IIIIIIIII I 111 11111 III III III II11
••       	11	1! ill 	IN	IlllilK tm\m» (illlliijlil II!	111	II'nili	Iiii	I  In ,4-10                              Sejrtember	1994	
                                          •1 iiii n iiiii i n  in i inn  i in in n i ii n n i in i i inn in iiinini i  ii iiiii i i  iiiinniin in 111 inn 11 inliiiiinn n in iiiiian

-------
.  EIA Guidelines for Mining	__	                        Environmental Issues

  Since individual samples will be used to test and classify larger volumes .of waste, it is important to
 .consider how representative samples are to be collected. Compositing is a common practice used to
  sample large volumes of material. Typically, composite samples are collected from drill hole cuttings
  on benches prior to blasting. However, compositing merges information about the variation of
  sample that would be identified if more samples were collected and analyzed.  Therefore, information
  about sample variability is lost (British Columbia AMD Task Force,  1990; Robertson and Broughton,
 undated). Composite sampling of tailings may be useful as a "first look" for characterizing tailings;
 compositing with stratification by lithology and alteration can help to avoid the problems of simple
 composite samples (Schafer, 1993).

 To be most effective, sampling programs for acid generation prediction should not be confined to
 initial prediction during mine permitting. The uncertainties associated with sampling, analytical
 techniques, and prediction methods all serve to make continued sampling and prediction appropriate
 throughout the life of a mine.  This can allow early identification of changed conditions that can lead
 .to problems, and thus allow early intervention to prevent major impacts.

 4.1.2.2 .  Static Tests

 Static tests predict acid drainage by comparing the waste sample's Tnaxhrnim acid production potential
 (AP) with its maximum neutralization potential (NP). The AP is determined by multiplying the
 percent of total sulfur or sulfide sulfur (depending on the test) in  the sample by a conversion factor
 (AP — 31.25 x %S). NP is a measure of the carbonate material available to neutralize acid.  The
 value for NP is determined either by adding acid to a sample and back-titrating to determine the
 amount of acid consumed or by direct acid titration of the sample (the endpoint pH is dependent on
 the test method).  The net neutralization potential (NNP), or acid/base account (ABA) is determined
 by subtracting the AP from the NP (NNP = NP - AP).  A ratio of NP to AP is also used. An NNP
 of 0 is equivalent to an NP/AP ratio of 1 (Ferguson and Morin, 1991).  Units for static test results
 (AP, NP, and NNP) are typically expressed in metric tons of calcium  carbonate (CaCO3) per 1,000
 metric tons of rock.                                                      .                .     •

 If the difference between NP and AP (i.e., the NNP) is negative then the potential exists for the waste
to. form acid. If it is positive then there may be lower risk. Prediction of the acid potential  when the
 NNP is near zero (between -20 and 20) is especially difficult  (Brodie et al., 1991).  Similar to Brodie,
 Smith and Barton-Bridges also suggest an NNP criteria of greater than 20 where the risk of acid
generation is low (Smith and Barton-Bridges,  1991).  Other studies conducted by the State of
Pennsylvania on surface coal mine drainage suggest that sites with an NNP of greater than 10 exhibit
alkaline drainage, with a gray zone ranging from 1 to 10 (Brady et al., 1994).  Finally, the State of
Tennessee has encountered acid generation (along with elevated iron and manganese levels) in
backfilled portions  of six area coal mines, where positive NNPs were initially observed (some
samples had NPPs between 5 and 20,  but averages were generally greater than 20). The
                                            4-11                             September 1994

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           	Environmental	Issues	
                                                                  	EIA Guidelines, for Mining
                                                                        iiB^    	       •    	'isiiim	iiw
            „	_	:	
            inconsistency between test results and actual conditions has been attributed to carbonate materials with
           ;;;	slow	djssdutionxate^	heterogeneity between carbonate and sulfidic materials, and the availability of
                                                                                                             ItflMW	Ill
                      ...... SSi
                                            SHI ..... Sll I ...... fits ..... Sfil ....... if 4 ..... §iPPle's neutralization potential to acid
  =        ^production potential is greater than 3:1, experience indicates that there is lower risk for acid drainage
	_	-J	!t- * ,;  . .j»   ' '••   I'1	»'•' " •' ' '•  	'	 .', . : . .	 ,.,  •'   	 • -'  •  •	'•  	i'1	' '  f-'IT  '-,	  ',.|T   >,&  •
           to develop.  Those samples with a ratio of 1:1 or less are more likely to generate acid. Brodie refers
           to ratios between 3:1 and 1:1 as the zone of uncertainty, where additional kinetic testing is usually
           reco^nmended and acid mitigation measures may be required (Brodie et al., 1991). Data from coal
           mines in the eastern United States indicate that an NP/AP of greater than 2 A is required to ensure
           acMl will not bereleased, (Cravotta et al., 1990).  ^Finally, data from a single Canadian mine stow that
           an NP/AP of up to 4.0 must be maimafrwid te-provide for near neutral drainage.  Morin and Hurt
           suggest that the criteria for detennining ABA should be established based on site-specific conditions
	i	I	(Morin and Hutt, 1994).      *                 .
 *
           in1 if in
           non-acidic conditions ^(tie early phases of ARD are often under pH neutral conditions), coating of
           carbonate grains by precipitated hydroxides, and climatic factors that lead to faster weathering of
           catf)0nac£0us materials than sulfide materials (Day, 1994). When reviewing data on static tests, an
          waste or
[[[ SS  ..... ,S£ .....       ...... SaSSl ......
                      in ..... Exhibit
                                           IS! ...... S2SlSS|!Pg static testing. Five types of static tests are
                                                                       '
    11 IF in i
	orative	,S!2!!,	,525, Performed by Lapakko (Lapakko, 1994a)ona
wSc range of sampjes using the ABA/fte modified,ABA, the BC method,' and the, modified BC test
IIIIIIH
          methods (pressed by Lapakko). Lapakko's results suggest.that the ABA and modified ABA methods
          tend tQ overestimate actual neutralization potential (and potentially underestimate acid generation).
          ""- nC and modified BC methods results most closely correlate to the actual mineralpgic NP.  As
                t in Exhibit 4-|s	the	modified	Bg	process determines NP by titrating to pH = 6.0 rather, than
          The
          •v-                                                                         ''
          Kinetic tests are distinguished from static tests in that they attempt to mimic the natural oxidation
          reactions of the field setting. The tests typically use a larger sample volume and require a much
          kni"" time for completion than do static tests. These tes|§ provide information on the rate of sulfide
          mineral oxidation and therefore acid production, as well as an mdication of drainage water quality.

-------
EIA Guidelines for Mining
                                                   Environmental Issues
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           Environmental Issues	EIA Guidelines for Mining

	           Of the different kinetic tests used, there is flo one test that is preferred.  The preference for tests
          1 changes with time as experience and understanding increase.' In a 1988 summary article by Ferguson
           and Erickson, the B.C. Research Confirmation Test was considered to be the most widely used.  A
           similar  1991 article by Ferguson and Morin stated that the use of modified humidity cells was
           becoming more common, and mere seems to be a trend toward the preference for modified humidity
           cell and column type tests.  Six types of kmetic tests are summarized m Exhibit 4-2.

           Kinetic tests can be. used to assess the impact of different variables on the potential to generate acid.
           For example,  samples may be inoculated with bacteria (a requirement for some tests). The
           temperature of the sample environment may also be controlled during the test. Most tests require the
           sample particle size to be less man a specified sieve size (e.g., minus 200 mesh).  Larger sample
          volumes and test equipment may examine acid potential from coarse particles. Acid drainage control
                                                  by adding lime,  may also be examined using kinetic tests.
                                                                               II-
          It is helpful to supplement kinetic tests with an understanding of empirical data characterizing the
          sample.  Examples include analysis of specific surface area, mineralogy, and metals.  Such
................ ! [[[ infojtma^gn ..... nog affect the interpretation of test data and are important when making spatial and
                                            es,based on the. test data. As with static tests, it is important to '
    J
          consider the ..... particle ...... size ..... of the ...... test ...... sample, particularly when comparing test results with field scale
          applications.
            .............................. I [[[ ;•• [[[ ' [[[ .................................................. ' [[[ '
          4.1.2.4 .............................. Application of Test Results in Prediction Analysis '                   .           '

          Results from static and kinetic tests are used to classify mine wastes on the basis of their potential to
          generate acid.  Static tests yield information about a sample's ability to neutralize acid and generate
          acid,,, JEedjSereoge ..... or ..... ratio ...... ofjhese ..... vajues.bjegojnes. ....... the ..... b,asjs ....... of .the, ...... classification. { As discussed
          above,  for samples with NNP values greater than 20 tons CaCCyi.boO tons of waste and/or jjp^p
          ratios of greater than 3.25:1, the potential to generate acid is low (Smith and Bartort-Bridges, 1991).
          For ..... NNP ..... values ..... tetwegi ..... :20 ..... and ..... 20 ....... j&fos between ........ 1:1 ....... and, ...... 3.25:1),  the potential for acid generation
          remains, and uncertainty will exist, (ft is important to note that each of these values are generalities
          and can be af&cted by a wide range of site-specific conditions that can either promote or retard ARD
          generation; the relative aya||abi|fty of surface areas of iron sulfides and calcium-magnesium
          carbonates, reaction rates, drying/wetting conditions, etc.)
                                                   •
          The determination of AP based on estimated or reactive sulfur content in the sample has some
          iaherem limitations. When total sulfur is used as the basis to estimate sulfide content, this uncertainty
          S2X ...... If, ...... aanbutabte ...... to possible ...... errors ....... in ..... (1) ....... assessment ...... pfjrue acidity and neutralization in the
          2£2£!e,i ........ SI ..... calculated ..... acidity based on total sulfur conversion value; and (3)  analytical error.  Similar
          errors pxist for static tests that determine reactive sulfide mineral concentrations.  Estimating long-

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EIA Guidelines for Mining
                                                     Environmental Issues
<
•


Exhibit 4-2. Summary of Some Kinetic Test Methods, Costs, Advantages, and
Disadvantages
'Humidify Cells
(Sohek«ud.r1978> -' -

-2.38 mm panicle size
200g of rock exposed to three days dry
air, 3 days humidified air. and rinsed
with 200 mL on day 7
cost: 425-850
''•'• .Soxhdei Extraction
(SingHnn and Lavkulich,. 1978;; Sullivan
- and Skibek, 1982)'
SUMMARY OF TEST METHOD
T=70°C (Singleton and Lavkulich,
1978); T=2S-C (Sullivan and Sobek.
1982); water passed through sample is
distilled and recycled through sample
cost: 212-425
x • Column Tests -,.. •
•(Brnynesteyn and Hackl. 1982; Hood
and Oenel, 1984)

variable panicle size
columns cotitHininR mine waste are
leached with discrete volumes or
rechculating solutions
cost: dependent upon scale
ADVANTAGES AND DISADVANTAGES
models AP and NP well and models
wet/dry;3 approximates field conditions
and rate of acidity per unit of sample
moderate to use. results take long tjine,
and some special equipment1
moderate ease of mterpretation;u large
Source: Lapakko. 1993b)

•":. '?%B -(Duncan -and Walden; 1975)
simple, results in short time, and
assessment of imenction between AP
andNP3
moderate to use and need special
moderate iiHe«iietation'J in
developmental stage and relationship to
' Batund processes not clear*

Batch Reactor .: ' ';••
(Halben et al;;;i983) j*? -MS . :
models AP and NP, models effect of
different rock types, models wet/dry,
and models different grain sizes1
difficult interpretation, not practical for
large number of samples3
large volume of sample2 lots of data
generated, long time,- and potential
problems: uneven leachate application,
• channelization3*3

., ,.; ' -. • -Field Tests.-. ••> '.
•%?*•?•• (Egerand.LapaHco, 1985)
METHOD
-400 mesh panicle size . '
15-30g added to bacteriauy active
solution at pH 2.2 to 2.5, T=35*C; if
pH increases, samole is non acid
-200 *ng
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          * "  Enrironmental Issues
I    II I II I I   I    II   II I       nll  III  I III1! 11

 EIA Guidelines for Mining
                                                 ,
              term reactive sulfide based on short-term tests may result in uncertainty due to difficulties in making
            * oxidatiqn rate predictions (British Columbia .AMD Task Force, 1989).
              Acid base accounting tests conducted on an iterative basis, where the initial sample set is small, are
              helpful when establishing boundaries between lithologic units.  As data from static tests is collected"
                           , the sampling selection can be refined.. The goal of, sampling is to collect representative
              samples that define the variability of the lithologies present  If significant variability in the acid
              generation or neutralization potential is identified in the initial sample test results, additional sampling
              to refine ..... lithologic boundaries is 'necessary (California Mining. Association, 1991).
             Kinetic tests are often conducted to	confirm	results	of static	tests,	to	test the potential for ARD' hi the
             uncertainty	zones	of static testing, and	to	estimate	when and how fast	acid	generation	will	occur.	•	
             These tests provide insight on the rate of acid production and' the 'water 'quality potentially produced

             method for evaluating test results. Data are examined for changes through time and water quality
             characteristi.es.	'	Kinetic tests tend	to	accelerate the natural oxidation	rate	over	those, observed in the
             field.	This	may have lie advantage of condensing.time, and providing earlier insight into the


         ......................... :. ..... potential for acid generation.
         •IB  .....
                                                     ............. ................ Jill .......................... If. ..... I ............. i! ..... *,. ...... ! ........ ' ............. .i! ................ l> ........ ,;• ....... I ....... I ........ I ......... ij| ...... ' ....... Illiiill ......... IK ........ (Ilill! ......... ill ..... i ............ I ...... inn* ..... !!li| ..... •  ........... 'ill ........... Ill ........ | ..... i>> ...... /P! ..... Hill!1' .....
             Generally,	kinetic tests	are	evaluated	for	changes	hi pH, sulfate, acidity and a host of potential ,
             According to the British Columbia AMD Task Force (1989), samples with pH values less than 3 are
	.	i	;	,	considered	strongly acid; between 3 and 5 the sample is acid-generating .and there may be some
	;	"	neutralization occurring; at pH values >5, the sample is not significantly acid or an alkaline source is
             neutralizing the acid. Sulfate is a by-product of sulfide oxidation and can be used as a measure of the
                                                 i. When evaluating test data it is important to examine the
                                      ion curve as an indicator of sulfide oxidation, in addition to other
            	parameters.  An analysis of metals in the sample solution serves as an indicator of contaminant load
                   not usually a good indicator of acid generation.
            4.1^^	Experience With Static and Kinetic Tests
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                                                         : of mines it is easy to determine the likelihood for acid
     ""      generation to be a problem. For some, acid generation would be expected; for others, it would
            definitely not be expected. Predicting the potential for the other 50 percent is more difficult (U.S.
            EPA, 1992). When data collected from static and kinetic tests is inconclusive, it may be necessary to
       	extrapolate from existing data using oxidation rates and other factors and project how a sample may
    	 	~  ^^       	«|  I	        '              ,                     '     II,	_,	I	;*,„	,*	
            reiMct.  The soundness of the extrapolation is dependent on the representativeness of the sample, -
            accuracy_of Jhe tests data, and the interpretation of the data.
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                                lilH^^^

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 EIA Guidelines for Mining	Environmental Issues

 Ferguson and Morin (1991) found that samples with an NP/AP ratio of less than 0.1 tended to
 produce acid during typical laboratory timeframes.  They expected that if laboratory tests were
 conducted for longer time periods the NP/AP ratio would shift closer to 1 and did not speculate on
 what the values for NNP and NP/AP would be in the future.  Extrapolating a sample's ability to
 generate acid was divided into short (less than one year), medium (a few years), and long term (many
 years) time frames. Short-term projections are based on laboratory data. Medium-term projections
 require knowledge of the neutralization process, primarily consumption of carbonate.  Long-term
 extrapolations of acid generation potential will require an understanding of weathering rinds and
 diffusion of oxygen into and reaction products out of that rind. Long-term projections were identified
 as being extremely difficult.

 Researchers hi British Columbia have examined results of static and kinetic tests conducted on tailings
 and waste rock (Ferguson and Morin, 1991). The results are based on a study of 20 active or
 abandoned mines in British Columbia. Their findings indicate that for tailings, only those samples
 having a negative NNP produced acid. The test method was not identified and the limitations are
 therefore not discussed here.  According to mis report, waste rock data from static tests is very
 limited and demonstrates the variability expected with these waste units.  They observed that samples
 of waste rock that had weathered for one month (prior to sample collection) needed to be flushed
 initially to remove existing oxidation products.                   ,

Lapakko (1990b) used solid phase characterization of the sample in conjunction with acid base
accounting data and the rates of acid production and consumption to extrapolate information beyond
the timeframe of kinetic tests.  The rates of acid production and consumption were based on kinetic
test results over a 20-week period.  The time required to deplete sulfide and carbonate minerals was
determined using rates established from kinetic tests. Based on these observations the .time required
to deplete the iron sulfide content was 950 weeks and the time to deplete the carbonate content was 40
weeks.  This prediction agreed with an observed drop in pH between week 36 and week 56 from 8.7
to 6; after another 20 weeks the pH dropped below 5.

4.1.2.6   Mathematical Modeling of Acid Generation Potential

As the preceding discussion indicates, static and kinetic testing provide an incomplete picture of the
potential for mine wastes to produce ARD. Static testing estimates the ultimate AP and NP of waste
material but is generally silent with regard to the rates of generation of acidic and alkaline flows in
actual waste matrices. Kinetic testing is more helpful with regard to estimating the rates of oxidation
and neutralization within waste units. However, as discussed above, actual waste units can be very
non-homogenous and anisotropic with respect to the distributions of mineral types, particle size,
hydrologic conditions and so forth. Thus, while a given kinetic test may well approximate the
potential for ARD hi a portion of a waste unit, the result may  not be representative of the "global"
potential for ARD.  Equally important is the practical limitation on the duration of kinetic tests:


                                            4_17                              September 1994

-------
                 llllllllll III 11 III 111111
                       ^
Illlllll ill Illlllll III"
      Environmental Issues
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                                               I I'lllll
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                                                     ,                                         ,
                                    	lead	to	erroneous	cgrahunoiB if they result in the omission of important
                                 instance,	failure	to	consider the presence of neutralising mat-rials in & -waste
         pile could result ^ an overestiniation of the rate of acid generation. Similarly, failure to consider
         hydrogeochemkal conditions within a waste pile may pzsc&de consideration of adsorption/
         precipitation reactions involving metais, thereby miscalculating the potential for metals loading in
        	effluent	streams.	Because the	importance of any given crairmUmg factor may vary from site to site
         (and from time to time), me sigmficBice of a snnplifymg assumption far any particular modeling
....... effort 'must ...... be
                               "carefiulyT .......
       	Empirical Models
         As stated above, empirical models extrapolate values of sulfide oxidation from existing laboratory and
         field test data.  The method of extrapolation typically involves determination of the "best-fit lines"
         through test data points (British Columbia AMD Task Force, 1989). The equations so derived may

                                                      4-18
                                                                                September 1994
 	Ij	i    i   "ii1	i	i	    i     ni

-------
 EIA Guidelines for Mining                                               Environmental Issues

 then be solved to provide, for instance, the acid generation rate of a particular waste unit at some
 time in the future.  Using the projected acid generation rate as an input to a separate
 hydrogeochemical model that accounts for attenuation of seepage constituents in soils and dilution in
 receiving waters, the estimated constituent loading rates and consequent receiving water quality at
 time T may be estimated (Broughton and Robertson,  1991).

 Empirical models generally do not explicitly consider the causal mechanisms driving oxidation of
 sulfides and neutralization of seepage. Rather, such models assume that the operation of such
 controls is accurately represented in the test data,  Therefore, the accuracy of empirical models  in
 predicting ARD depends heavily on the quality of the test data used in the models.  Principal sources  .
 of uncertainty may be expected to include variations in the spatial and particle size distribution of
 sulfide and alkaline minerals not captured by the data due to insufficient spacial distribution of
 samples; changes in the distribution of particle sizes throughout the waste unit (due to weathering) not
 captured by the data; and failure to accurately calibrate the model to reflect the actual quantity and
 type of materials (British Columbia AMD Task Force, 1989).

 It is important to note that empirical models, by then: nature, are site-specific.  Because the models
 rely on actual trends observed at a specific site, rather than generic causal mechanisms, the best fit
lines for one site cannot be assumed to be representative for another site.  Further, significant changes
in waste unit composition, geometry, or controls over time may invalidate previous representativeness
of empirical models. Nevertheless, empirical models may provide cost-effective and reasonably
reliable estimations of short-term future ARD conditions for sites with sufficient spatial and temporal
data.

Deterministic Models

Deterministic models simulate ARD.by solving systems of equations that represent the various
controlling factors in the waste reaction process (Broughton and Robertson, 1991).  The simulation
approach allows the users to examine the  potential sulfide oxidation rate and resulting seepage quality
over periods of tens to hundreds of years  in the future.  The greatest promise of deterministic models
is that they may allow the user to predict  ARD as  it evolves over time under the changing influence
of rate-controlling factors. Existing models have built upon earlier work on acid releases from coal
mine spoils as well as work on leachate quality in  metals heap leach operations (Nicholson, 1992).
The models may rely solely on the causal relationships described in the equations, or may include
empirical  data as exogenous drivers (outside the model structure) to solve for certain aspects of the
system (Nicholson* 1992; Broughton and  Robertson,  1991). The most important differences between
the models lie hi the particular causal mechanisms (e.g., oxygen diffusion, changing particle size,
 temperature variations due to exothermic  reactions) addressed within each model structure.
                                             4_19                              September 1994

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                                                                             EIA Guidelines for Mining
           Nicholson presents a review of ARD models, in that review, Shumaten (1971), as cited in Nicholson
     [[[ ffSls ........ £ ....... S2S22 ....... SS£,,SS5S ...... reggfijzing *£ ...... SS2S ...... of&ygen with™ nun6 rock limits the, overall
           raf6 of oxidation of sulfides (Nicholson, 1992).  The first working models to incorporate this process
           (Mortfa, 1972; Rica and Chow 1974; both cited in Nicholson, 1992) used the acid generation rate to
           calculate resulting drainage water quality.  Rittchie (1977),'as cited in Nicholson (1992) added to this
                 ..... "•* ...... 3"«2 ..... "22153 ....... fo,L£e, ..... SSSi ....... 2l,,s£3S ..... sife ..... Ssi ...... Ite ...... gsss ...... sCssisfele
    il ............................ ....... pnreacted sulfide. Jaynes et'al'., working ^wftfa a model of pyriticsiiaie ...... in ..... coal-mine ...... spoils, assumed
          pyritic particles to oxidize as shrinking cores of unreacted material surrounded by an outer layer
                                               e                 ...... ,52, ..... §E!S5S! ....... SS13S2I ...... ass, ...... atpxygen,
               ;	&«	£J!jiJ5£gi§	£25	grovidesa	smaUerjrcactive	surface	area.	^ermodelg,	have	incjud.ejl	
         	cbnvecSon as a means of ,ox|gen" transport within waste piles (Lu and Zhang, undated). Convection
	i	may tejjnfiuffl^ed	by_	ichaiges	in	barometric pressure or by the release of heat from the exothermic,
                  ; of SMlfifieg,.,,	Ssmg	jeisficierstove modeled the feedback;mechanisms operating between
                      nd^ojogcal and chemical oxidation rates, noting that the, mechanism is only significant
               32SS P*1:!!??3^1*68 a"^^gh enough to allow convective oxygen transport to occur (Nicholson,
          1992).
                    .            .....         ^Ae Igrdrolggc ...... and^geTChemical ....... conditions,, m ..... waste unit matrices,
         as well as reaction product transport, to more realistically represent changes in seepage quality
         (N^^kpn? 1992). Bennett (1990) andoifaers found that water flow through the waste pile strongly
         influencf2l ...... 2S£ ..... 23JjJ!ttj
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       Guidelines for Mining           	-	     Environmental Issues

  Notwithstanding the understanding that existing models have provided, ARD models to date have not
  found extensive applications in predicting oxidation rates and effluent quality at operating or proposed
  sites (Ferguson and Erickson, 1988). As stated above, models are simplifications of reality, and
  consequently are subject to a high degree of uncertainty.  Among the sources of uncertainty are
  incomplete or invalid model structure; natural variability of certain parameters; and lack of parameter
  calibration and model verification (British Columbia AMD Task Force, 1989).

  Incomplete model structure leads to uncertainty in predictions by ignoring potentially important rate
  controlling factors.  In general, incomplete model structure .results from an incomplete understanding
  of the system being modeled, or the overuse of simplifying assumptions (British Columbia AMD Task
  Force, 1989). For example, failure to accurately account for water flow within the waste matrix    .
  prevents consideration of the thermal gradient within the pile, the transport of oxidation and
  dissolution products, and the conduction of oxygen via water. It is worth noting that modeling water
  flow in waste rock piles presents greater difficulties than in tailings piles, and has received little
  attention to date (Nicholson, 1992). For this reason (among others), waste rock pile models are
  subject to a higher level of uncertainty.

 Natural, variability of some parameters of a system can lead to uncertainty in model predictions.  For
 example, changes in rainfall patterns, which directly effect the hydrologic conditions in the waste pile,
 are difficult to predict with certainty. Likewise, particle size  distribution and mineral type distribution
 throughout the waste pile can be highly variable and difficult to predict.

 Among the greatest concerns lacing the reliability of predictive deterministic models are model
 calibration and validation.  Model parameters must be adjusted to match the conditions prevailing at
 an actual she. Therefore, reliable waste characteristics, hydrologic and geochemical data must be
 collected and incorporated into the model structure. Validation requires  comparison of model
 predictions with actual field sampling results. To date, the availability .of field data for validation is
 very limited.

 4.13    ARD DETECTION/ENVIRONMENTAL MONITORING
                                    •>
 Where there is the potential for encountering sulfide mineralization, an assessment of potential
 impacts should include appropriate testing for ARD potential (using one or more of the methods
 described in the previous section).  Where testing results demonstrate  potential for ARD generation or
 where such test results are inconclusive (particularly in sensitive environments), an applicant's
 environmental monitoring program should include specific testing directed at early identification of
 ARD.  This should involve sampling of effluent streams as well as surface water and groundwater.

Existing data on ARD generation indicate that it is highly variable.  (Mine discharge sampling data
compiled by the British Columbia Acid Mine Drainage Task Force at sites with known ARD
                                             4-21                              September 1994

-------
            Environmental Issues                                                EIA Guidelines for Mining
            generation show significant day-to-day variability in pH and concentrations of dissolved metals.)  As a
            result, regular monthly or quarterly sampling ([commonly used to monitor effluents/impacts from
    || 11| illllJ nil j|||||||||jjj||||||||l I llJlllllllllllllllll IIJII lllllllllllllllllllllllllliiilllliilllllllllllllli                     	ill	II	Ill	II	liliiiiillll£llliilllillillllllllllllllilllllililliilillli!lli          	I	Illlll	I	II	Illil	Ill	I	|l	II	I	lillnl	II	li|i|lil|||ii||||l III i IIII ' || II  " j\ II	|i|	iinliwiiiililni	.nr	iiiiinniih
    	industrial operations) may not be adequate to detect ARD generation. Where ARD is a potential

            concern, baseline studies	should	be	designed	to	establish	conditions	where	ARD	is likely to	occur.	

            Monitoring programs during and after operations should be tailored to address the factors that affect

            ARD generation.  These factors include:
                 *   Seasonal Variability. Most mines where ARD is observed exhibit seasonal variability in
	'"!	"	ARD generation (except underground "adit discharges which" are	relatrvelyulu^pactied by
~= •"-" |':	~ "'™      changing	seasonal conditions).	Generally, either the first rain after a dry season or high
	!!!	"	'	35owm§(t	pencils	——--^	gggjy	to produce ARD. (ARD generation can be' specifically
                     increased by the buildup of salts on rock surfaces during dry conditions.)
                           I	', • •:       .                I.        ,  •       '•'   ;   ','  •   '[
                 '   Treated Effluent Variability. At mine sites, the treatment system effluent quality may be
                     variable due to different influent volumes and characteristics—for, example, where natural
                     conditions affect the influent flow and composition. For example, potentially acidic mine
       UH||i  .  I,	„  (|  water and runoff may be significant influents to the system under" certain "conditions.  "  '
                      	I1"'	       i           ^             11     ""  11 iill  '    i  i
BBIBfiiji ' ii ii •   Impacts on Aquatic Life. The actual effects of ARD on	a receiving water may be  •
                 .   dependent on the behavior/occurrence of specific	aquatic	life	within the watershed.	For
                    . example, the presence of migratory species may suggest the need for monitoring during
m^at	in	mm	iiiiii     specific time periods.  Similarly, seasonal releases of ARD may •occur during critical life
••'	>l	!•*'	I)M* stages of inuiviiiiial species.         '            '   '      •'   "       '  '
                •   Stream and River Effects. Streams and rivers may be heavily impacted due to .sudden
                    high releases of ARD (especially where there is limited dilution).  In snowmelt areas,
     	I	impacts can be particularly significant when a melting at the mine site occurs during a
                    different time period than other areas within the watershed (thereby reducing dilution).
     	I	Sampling plans should consider when "maximum" flows/discharges can be expected.

     	 • "  Lake Effects.  In lakes, the, effects of ARD may be impacted by physical and biological
                    conditions in the lake.  In designing a monitoring plan, factors such as thermal
    	[	"	stratification, turnover events, flushing rates, and .seasonal .cycles of aquatic life growth.
                    should be considered.         '                                               ,
                                   ,1'
                                jii         •.   ..... ,•                  .  , ••!> .    . •„.„:;=,,..'   .-  >,- .....  ,,.  ,     •  ,
          As stated above, baseline and operational monitoring programs should be designed to address each of

•iiiiH^^   iiiiiiiiiiiiii the above factors. A reasonable; cost-saving option is to provide for frequent pH or other ARD
|«          111 Illlll I. I    I   ........... I ........ I [[[ ............... I ......... I ................... I .................... "I [[[ I [[[ '=>' ........ .......... * ..... ! [[[ — [[[ i .............................................. =- [[[ • [[[
!'"' [[[ indicator (suliate, ........ alkalirugr, ....... etc.) ....... mpnftonnj; ...... of ..... effluent ..... discharges ....... and ...... ground and| surface ...... water ................................... . i

          quality.  When ..... indicator parameters exceed thresholds, increased monitoring could be required for

          other parameters (including metals and toxicity) to determine the extent of ARD releases/impacts

          (British Columb^AME) ...... TasJcFprcej .......... 1990).              '
          4.1.4    MITIGATION OF ARD

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  EIA Guidelines for Mining 	       •	Environmental Issues

  completely avoiding mining in areas with the potential to form ARD may be difficult due to the
  widespread distribution-of sulfide minerals.  The individual applicant's pre-project testing (using the
  methods described hi the previous section) should be representative of each rock type, provide good
  spatial coverage, and be proportional to waste quantities. As discussed above, this may frequently
  require collection and analysis of an extensive number of samples.  The results of truly representative
  sampling should allow the applicant to develop a mine plan to avoid, wherever possible, sulfide-
 bearing/acid-generating rock.'                                .                    -

 Effective isolation of wastes (backfill, waste rock, or tailings) with the potential  to develop ARD is a
 key element to conducting mining activities while minimizing perpetual effects to surface water and
 groundwater. In isolating these wastes, the acid generation process is brought under control. The
 requirements for the formation of ARD, as discussed in previous sections, include the presence of
 sulfides,  oxygen, and water. Control of materials with a potential for acid generation can therefore
 be implemented by preventing oxygen from contacting the material (or minimizing oxygen contact),
 preventing water from contacting the material, and/or ensuring that an adequate amount of natural or
 introduced material is available to neutralize any acid produced.

 The following sections generally describe specific types of mitigation measures for ARD control.  For
 the most  pan, only limited 'data are currently available to document then; effectiveness. Further,
 individual site conditions significantly impact their feasibility and performance in the field.  In many
 cases, the measures discussed below .are most effective when used hi combination and adapted to the
 situation existing at a specific site.

 4.1.4.1    Subaqueous Disposal

 Where fluctuations in water levels are not expected, placement of acid forming materials below the
 final potentiometric surface may be an effective means to exclude oxygen.  Similarly, some dry waste
 management units  can be closed  by flooding/subaqueous disposal of potentially acid generating
 material.  The water must be of a sufficient depth to ensure that it is not well  oxygenated (since
 sulfide can oxidize in subaqueous environments) and it should not pass rapidly through the system.
 Wetting conditions must be permanent and physical mechanisms must not be present to allow
 entrainment of wastes in the water.  Further, it should be noted mat metals found in waste materials
 can dissolve into neutral waters.  Both Lapakko (1994b) and St.-Amaud (1994) have suggested
placing  protective layers over acid generating tailings disposed of hi a subaqueous manner.  Similarly,
mine operations  hi upland conditions and hi drier portions of the west may not be able to consider
submersion as an effective mitigation tool for acid formation.  (See also Section 3.2 above.)
                                             4-23                              September 1994

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                                                                     	I	U	Ill
                                                                     iiiiiiil'iniii1 IP* nil inini
                                                       ill III ill I" II f ill Ihil11 'III 1111 II Illllilllllllll^                             !! I !  ml '»ilil »i|i|ii|l»»ll'lllp »»l'
                                                        i II in mil i mill ii inn n nil p inn iiiiiiiiiiiiiiiiiiiiiiiii inn i null iiiiilllliillll liniillllllll i|iilii|l|lllll|i|l|i|lj|i|ii|ll|i|l|i||ii|lill II1111 nil II lill|ii||i|llillllllll|ii|l|i|l II 11! n p in I nil i in mil! lilll|llllllillllllllilllll|i|lll
            |

         4.1.4.2    Covers
                        Issues                                               EIA Guidelines for Mining

       	±g»S	£°52iSa	         	Si	!2	SSLBSE	(and oxygen) from acid forming materials is the use
         °f MOW permeability cover.  Covers may consist of compacted soils or synthetic materials.  Proper
                	        	ESS68 to* meir integrity remain intact; those subject to erosion, weathering,
         SS2i!         or Penetration by plant roots may not provide adequate protection for an indefinite
        period of time.  Most (if not all) cover materials are more effective, at controlling infiltration of water
        than excluding oxygen.  By reducing the amount of water infiltrating a covered system, the potential
        for migration of any acid drainage formed beneath the coyer also is reduced.  Similar to covers,
                                     can be installed near §e highwaU to isolate disturbed areas from
              !:  *2S^y> during actual waste disposal, mines can segregate materials to minimize acid
        generation potential.  For example, carbonate materials can be placed on the surface of piles, while
        potentially acid generating materials are placed below the surface.
          "  (   '         '''.:•                  •       '   i    ' ' ' ' '  '• ' ^                     '   •
        _  L   	       -  ' ..  ,         • ..    •  ,          -.     ,v,i         •     ...  i     •-.	•	:	
        The Invitations imposed by covers are availability and costs of cover materials. If only limited
       "SSlSfSS	2£fi&SBfl3$g4$	SHSWRfl	over the life of an operation, those wastes which require special
                ™^ be precisely identified in the field.  In coal mining operations, the complexity of the
       situation is compounded by the requirement that reclamation be contemporaneous. In these cases, a
       special waste disposal area is generally not permitted for extended periods of time.
      	i	                                                    "	!	'i
       4.1.43     Waste Blending
        	:::,	  ...    ..'''iii  *?	             „ ,     ' , h   * , ,        ,     	
       Blending activities during the mining operation may be used to mix alkaline materials with acid
       fonnmS mattrials 'Witoi* a* T^te disposal unit.  The effectiveness of blending wastes is directly
       ****? *° ** ^reallieri°g Properties of the alkaline materials; if a CaCO3 equivalent is available at a
       rate equal to or exceeding the oxidation of sulfides, acid formation could be adequately controlled.
      Ill AlL^«feI»V«^ M
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   EIA Guidelines for Mining	"   .        	Environmental Issues

   disposal facilities. French drains may also be installed to promote ground and surface water flow
   underneath a disposal unit.  However, french drains constructed under disposal units (waste rock
   dumps, head of hollow fills) that eventually generate acid can function as a conduit for acid rock
   drainage into surface waters.

  At some metal mines, acid-forming waste rock is being  "encapsulated" within larger waste rock
  dumps. Relatively low-permeability neutralizing material (often waste rock from other lithologic units
  that is compacted) is placed under and/or over sulfide rock.  The intent is both to reduce water flow
  to and through the sulfide rock and to neutralize any acid that may form.

  4.1.4.5    Bacteria Control                        .

  Thiobadllus ferrooxidans is  the principal organism responsible for the bacterial oxidation of sulfides
  that may dramatically (up to a fivefold) increase the rate of acid formation. Studies using bactericides
  to control ARD have been conducted with some degree of success.  A summary of the effectiveness
  of bactericides presented by the British Columbia Acid Mine Drainage Task Force indicates that these
  compounds can effectively reduce acidity by 50 to 90 percent (British Columbia AMD Task Force,
  1989).  However,  bactericides are degraded and leached with time,  ultimately having a limited life
  span. Additionally, if acid generation is occurring hi an  absence of bacteria, bactericides will only
  control  the rate and not the presence of ARD.

.4.1.4.6    Treatment

- Mines currently hi operation experiencing acid mine drainage may face a*costly and long-term battle.
 If acid drainage develops (as it often has) unexpectedly, well after waste disposal units have been
 constructed, mitigation may require extensive earth moving activity, if sources are small enough to be
 pinpointed.  Alkaline material (e.g., lime) may be added  in solid form to flows moving into or out of
 the acid-forming area (the use of "sorbent" polymers and microorganisms is also being studied). The
 effectiveness of raising the pH of the water before or after contact with acid-forming material is
 limited by the chemistry of the constituents involved, and the volume of acid being produced.
 Demonstration projects'have made use of injecting alkaline solutions into acid producing material;
 however, the long-term effectiveness of this treatment has not been documented (Bureau of Mines,
 1985).

 Anoxic limestone drains (ALDs) are currently being studied as passive treatment technologies.  The
 Tennessee Valley Authority has successfully used ALDs to enhance  the performance of constructed
 wetlands (Brodie, 1991).  Combined ALD and wetland treatment systems have also been successfully
 tested in Pennsylvania (Hedin and Watzlaf, 1993; Rowley et al.,  1994).  However, limited data are
 currently available  to assess the long-term effectiveness (including potential limiting factors, such as
 coating of limestone surfaces with iron and aluminum oxides) and widespread applicability of ALDs
                                              4-25                              September 1994

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         Environmental Issues
                                                                         EIA Guidelines for Mining
         in mitigating ARD, especially where they are used alone. In addition, design of ALDs or any other
            II         ,11                   ,                      i     i        i i        ii .   I,
         alkaline/precipitation treatment system must include a settling area.  Hedin and Watzlaf (1993)
         provide additional information on the design and performance of ALDs.
         In cases where mine drainage is only slightly acidic and metal loadings are low to moderate, natural
         and constructed wetlands show some ability to improve water quality (Brooks et al., 1990). In
         wetlands, "treatment" of ARD (and associated metals) occurs through physical (settling and
            I      '    '  ',f  ,  '   "	:         "      ;.            ,,		•   ' f  	 .::  	"\,r   .,.,      . ,,
         adsorption), chemical (hydrolysis and oxidation), and biological (bacterial desulfurization) processes.
         Cohen	and Staub (1992) provides technical guidance on the design and operation of wetlands
                  systems. Based on data from	an operating	wetlands treatment system at the Big	Five	
         Tunnel in Idaho Springs, Colorado, an effective life of approximately 4-6 years is projected for a
        PHI	i	1	_	i	i	liil	II	H	,. * < II      <   < «      i PL   <    ll N         I i   II
         single loading of substrate material (Cohen aid Staub, 1992). At some sites, operators may need to
        	provide separate	areas	for	anaerobic	(chemical/physical)	and	aerobic	(biological)	processes.	Based	on
        a study of six artificial wetlands constructed by the Commonwealth of Pennsylvania, a surface flow
       	|	'	_	;	;	;i	;	i	i	;	,	i	,;	,	"	|	,	;	
        criteria of 6 grams/day/square per meter was recommended (Dietz et al., 1994).
 iiiiiiiiii
    Testing conducted by the Commonwealth of Pennsylvania has'shown that passive wetlands treatment
    can be effective in mitigating ARD for coal mines, especially for mildly acidic drainage (performance
    of more than 73 wetlands was evaluated).  However, it should be noted that study results generally
    showed mat treatment levels for metals were lower than predicted (Hellier et al., 1994).  Further,
    studies such as those performed by the State of Minnesota, have shown that the capacity of wetlands
    for metals removal is often limited.  The Minnesota study found that metals removal was limited to
    me upper 20 centimeters of a constructed wetland and that limited-flows/periodic maintenance would
^m Jill nllil iliii	i	(ii	liil	                                    f
    be necessary to provide long-term mitigation (Eger et al., 1994).
        While combined ALD and wetland systems show some promise for passive treatment of highly acidic
        streams (Rowley et al., 1994), current data to support then* widespread effectiveness and feasibility
||H    are limited.  Therefore, where flows contain low pH values and nigh'metals concentrations, 'active
II11 111    11 111 111 l|llllllll      •  111^^ IIIM    llllllllllllll llllllH   llllllllllll 111111 111 111 111 11111 llllllllllll III              I                 |
        long-term treatment may be necessary to achieve acceptable water quality in the mine's discharge. A
        potential alternative to conventional active treatment practices (neutralization/precipitation with lime,
        etc.) involves the use of Sulfate'Reducing Bacteria (SRB) to treat acid drainage.  SRB decompose
        organic compounds and produce sulfide  (which is either given off as hydrogen sulfide gas or reacts
           , metals to form metal sulfides). At  a February 1994 EPA workshop on SRB treatment, several
           icipants noted success  in reducing metals levels.  However, SRB performance data are still limited
   fndjigsults. ....... vary
                                                       ...... optimum design parameters,'
        Igpacts, ....... tpwcfty to ..... organisms, and hydrogen sulfide conttpl need' to be address (U.S. EPA, 1994).
         inally, Cohen and Staub note research indicating SRB are found in wetlands and are important for
              removal in wetlands treatment systems (Cohen and Staub, 1992).
                                                                                 ^^^^^^^^^
                                                                              IlilllH^
                                                                              	llltK^^^	ill' Kill	IlllR^^^       	••Ill

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 EIA Guidelines for Mining                                               Environmental Issues


 4.1.5    SUMMARY OF FACTORS TO BE CONSIDERED IN EVALUATING POTENTIAL ARD
         GENERATION/RELEASE

 ARD from coal and hardrock mining operations has been shown to have significantly affected aquatic
 life in thousand of miles of stream segments throughout the country.  These effects can be long-term
 and the costs of remediation are prohibitive where it is even feasible. - While there is extensive
 ongoing research on ARD, there is substantial uncertainty associated with virtually every methodology
 used to predict, detect, and mitigate ARD, Further, the extent of ARD generation and the potential
 risks are generally dependent on a wide range of site-specific factors. No assessment of potential
 environmental impacts of a proposed mine should dismiss acid generation potential based on limited
 test data, especially where sulfide  ore will be mined. In addition, care must be taken not to be
 overconfident hi the efficacy of specific mitigation measures that may be used if ARD  is encountered.


 ARD-related factors to be considered in evaluating potential impacts include:


      •   Comprehensive baseline acid generation potential testing of the ore and waste materials.
         Where there is any historic basis for believing that ARD could occur and/or where new
         sources are proposed in  particularly sensitive environment areas, the applicant should
         conduct testing of each geological unit as well as analysis of representative waste samples.
         Further, the applicant must be cognizant^of the areas/ranges of uncertainty associated with
         static testing. Where there is evidence ARD can occur or where static test methods indicate
         uncertainty, kinetic testing should be performed to determine the drainage characteristics
         (and facilitate mine planning).

     •   An ongoing environmental monitoring program to detect ARD  when it occurs. Sampling of
         wastes, discharges, and surface water/groundwater should be tailored to site-specific
         conditions mat favor ARD generation (e.g., monitoring during  or immediately after a major
         precipitation event after  a long-term dry period). An effective monitoring program should
         emphasize the need for a full understanding of site conditions, including hydrology,
         geology, and climate. Typical one-time quarterly or bi-annual sampling events may not be
         adequate to detect ARD.

     •   Where ARD could be encountered, detailed information on the design and operation of
         proposed mitigation measures (including a quantitative engineering assessment of then- likely
         effectiveness based on then* historic use under similar conditions).  If any uncertainties
         arise, operators should provide for contingencies if proposed measures are ineffective.

     •   An approach to reclamation bonding that accounts for the long-term impacts  of ARD must
         be cognizant of the potential for a significant lag-time/delay in ARD observance (thus
         necessitating care in bond release).  Also, the need for perpetual treatment measures (and/or
         perpetual maintenance of passive treatment techniques) should be considered.


While the potential for ARD generation is highly variable, extensive documentation is available on a
wide range of site conditions. Further information is available from the references cited in this
section and from many other sources. In addition, Canada's Laurentian University Library has
                                             4_27                             September 1994

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                          ......      [[[ , ...... : [[[ - [[[ EIA Guidelines for Mining
                                                                         Ji ...... : .......... ,""!™~, '! ...... „"'"" ' ..... '^';l', ,!'':v»^, '"' " , ,'. ,'  , ........... '
                :.  •  ,            •      -•       ,          :   •        • .    .' ,  ............... i  ....... •v:;" "'V    ,
             ,   Hshed the on-line Mining Database, which contains citations and abstracts, related to ARD and
           reclamation.  Finally, while there is no consistent National policy related to ARD, several regulatory
           entities have developed specific requirements to address ARD generation at new mining operations.
           For example, BLM has recently promulgated an ARD policy to guide approval of proposed
           operations (Williams, 1994).  OSM requires acid-base accounting to assess acid generation potential.
           f^»	, j- t   ' t_  T\ » •  	       '                    '              	    	
          •iSSSZl	2£	Brmsj^olumbja	government ^ has	sgecific requirements for .ARD prediction,
          ggjirgmnenfel	mOTutgrJng, mitigation, and bonding (Price and Errington, 1994).  Some States and
                   Forests	also	hay^poticies	rejatecHo jxrediction,monitoring, mitigation, and bonding. .
S"5?y    ,    AD   HEAP ICHING

                                                          For	decades,	it	hasjbeen	used	asa pyrite
                     in	base	metal	flotation.	ftalso	has	teeji used	fgj	over,	a	cejggry in gold extraction.  In the
          I9S)s, technologies that allowed laree-scale beneficiatinn of gold ores, using cyanide (first
          iSsnojogtrlgg,	a	gripple creek, Colorado) set the' stage for the enormous increase in cyanide usage
               jold prices skyrocketed in the late 1970s and 1980s. Continued improvements hi cyanidation
               F"	"r	nj"'	W"	"	"iiisr11'1*	rs	^	3	™i	:	~	:	:	;	,:;:	,:	:T"::	T,"1:":1"1	,:::	::;,	,'",""" r,	!:;;	,:"" ::~T~:,ii	::	~	i""::"n ~*,,,,	,    / 	
         "technology have allowed increasingly lower-grade gold ores to be mined economically. Together with
         ^.continued ¥& gold prices, this has resulted in increasing amounts of cyanide being used in mining.
         A substantial pro^jtion of sodium cyanide produced in the U.S. is now used by the mining industry,
                               *      ™                ..... leaching ...... Ojperations ....... (both ...... tank ..... and ...... heap leaching). in
                                            .......          .....        ......          .......     ......    .....   ......
                                        fOT ..... copper/molybdenum flotation, and much less than 5 million
                                              '            '         .    ' ................ '"• ........................ ...... '
                                                       '            '                        ililiii
       '~-~;foe_	2ff	!°5f!^	2£,5Siiii!	=	1	IS!?!	?!lliE	JSESlSSs	IS5	ISSSSi	SiSSlm	on	gig	use, of,;	:,
                ! ^n the Tninmg mdustry. When exposure occurs (e.g., via inhalation or ingestion), cyanide
                                                                       lal in a short period of time.
                                         operalions a^j cyanide usage proliferated, there were a number of
                                       i|||disiiw.hej| ..... gjey attempted to use tailings ponds or other cyanide-
         containing solution ponds (e.jg., pregnant or barren ponds). For example, operators in Nevada,
         g^Ugj^g^ ^ /s^Mi^Kp^^ ^Q regulatory authorities on over 9,000 wildlife deaths, mostly
         waterfowl, that had occurred on Federal lands in those States from 1984 through 1989 (GAO, 1991).
  '       &* addition, a number of major spakfaaye occurred, including one hi South Carolina in 1990, when a
         dam ^^ resulted in the release of over 10 mflUon gaUons of cyanide solution, causing fish kills for
         nearly 50 miles downstream of the operation.
               [[[ " ................................... i ......................................... i [[[                                                               ,

         to many cases, regulatory authorities— Federal land managers and  States— have responded by
         developing increasingly stringent regulations or, hi many or most cases, nonmandatory guidelines.
         These            *              ...... £25 ..... Mifegss, ...... $£,;desjgn of facUities that use cyanide (e.g.,
                         , ......      . .....         ......   .....       , ......   ,                                   ..,
         reqiiirin^recmnmending liners and site preparation for heap leach piles or tailings impoundments),
     III II 111 lllllllllllllllH  I        '       •   I ..... llliillf IlllilH      lllllilill ill1 '(I llllill I'll Illli ilPllllliill ........ Ill ll I ............. lull i III 1 ....... 1 ....... lllllll ...... Ill ..... Ill I ........ Ill ...... llllllllllll ........ lllllllllllllllllH ...... I liillllll ................ Ill ......... I'll .......... Ill .............................. I ....... I ..... II ............... I ...... I


                                                     4-28                              September 1994


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  EIA Guidelines for Mining            ,                                    Environmental Issues

  operational concerns (e.g., monitoring of solutions in processes and in ponds, and in some cases
  treatr-ent requirements for cyanide-containing wastes), and closure/reclamation requirements (e.g.,
  rinsiiu to a set cyanide concentration in rinsate before reclamation can begin).

  There are a number of major issues associated with evaluating the potential impacts of cyanide
  operations on the environment.  These include the complexity of cyanide's chemistry, uncertainties
  about its behavior in the environment, and inadequate laboratory analytical methods. These issues are
  discussed briefly .below.  .         '

 4.2.1    UNCERTAINTIES IN CYANIDE BEHAVIOR IN THE ENVIRONMENT

 4.2.1.1    Cyanide in the Environment
                                                                    •
 Cyanide concentrations are generally measured as one of three forms:  free, weak acid dissociable
 (WAD), and total.  Free cyanide refers to the cyanide that is present in solution as CN' or HCN, and
 includes cyanide-bonded sodium, potassium, calcium  or magnesium.  Free cyanide is very difficult to
 measure and its results are often unreliable, difficult to duplicate, or inaccurate.  WAD cyanide is the
 fraction of cyanide that will volatilize to HCN in a weak acid solution at a pH of 4.5.  WAD cyanide
 includes free cyanide, simple cyanide, and weak cyanide complexes of zinc, earimhm^ silver, copper,
 and nickel. Total cyanide measures all of the cyanide present in any form,  including iron, cobalt, and
 gold complexes.  Exhibit 4-3 shows one means of classifying various forms of cyanide.  Free cyanide
 would include the"readily soluble" simple compounds, and WAD  cyanide would generally include all .
 of the forms in the exhibit except the "strongly complexed cyanides. "-

 Aqueous cyanide (CN~) has a negative valence and reacts readily to form more stable compounds.
 Aqueous cyanide complexes readily with metals in the ore, ranging from readily soluble complexes
 such as  sodium and calcium cyanide through the complexes measured by WAD analytical methods to
 strong complexes such as iron-cyanide. At a pH below about 9 s.u~,  weaker cyanide compounds  can
 dissociate and form hydrogen cyanide (HCN), a volatile gas  that rapidly evaporates at atmospheric
pressure.  The stronger complexes are generally very stable in natural aqueous conditions.

Unsaturated soils provide significant attenuation capacity for cyanide.  Within a short time and
distance, for example, free cyanide can volatilize to HCN if solutions are buffered by the soil to a pH
below about 8 s.u. Adsorption, precipitation, oxidation to cyanate, and biodegradation can also
attenuate free (and dissociated complexed) cyanide in soils under appropriate conditions.  WAD
cyanide behavior is similar to that of free, although WAD cyanide also can react with other metals in
soils to form insoluble salts. (Hutchison and Ellison,  1991)

Free cyanide is extremely toxic to most organisms, and this form has been most frequently regulated.
Under the Safe Drinking Water Act, EPA has established a maximum contaminant level (MCL) of
                                             4-29                             September 1994

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           Environmental Issues
  EIA Guidelines for Mining
1 III
t "
!•
t
t



Exhibit 4-3. Stability of Cyanide and Cyanide Compounds in Cyanidation Solutions
' '* , • *
Classification -•
Free cyanide
Simple compounds
a. Readily soluble
b. Neutral insoluble
• salts
Weak complexes
Moderately strong
complexes
Strong complexes
S^y^SV Compounds^' •'"••'•*•• '•"
CN-.HCN
a. NaCn, KCN, Ca(CN). Hg(CN)j
b. Zn(CN),, Cd(CN)j. CuCN,
Ni{CN)2,AgCN
Zn(CN)/2, Cd(CNV', Cd(CN)^
Cu(CNV'. CuCCNV2, Ni(CN)4-2,
AgCCNV1,
FtfCNk-4, OKCN)^, Au^NV,
Fe(CNV3,
•V •.•.'•. "•''••$:' Solution chemistry
Extremely toxic. In natural waters below
pH about 83, HCN form is predominant.
Water soluble. Dissociate or ionize readily
and completely, to yield free cyanide and
metal ion.
Rates of dissociation and release of free
cyanide affected by light, water
temperature, pH, total dissolved, solids, and
complex concentration. pH and
concentration most affect stability and
extent of dissociation (breakdown increases
wim decreases in pH, concentration).
Iron is most common/ important- Very
stable in absence of light. Long-term
stability uncertain.
Source: Column 3. Mudder and Smith 1989; columns 1 and 2 cited in Mudder and Smith.

         0.2 mg/1 free cyanide in drinking water.  The Clean Water Act ambient water quality criterion
             f'iS,"     '    • "I',,,   ,11 ,     •  , ,,,	 "I  ."1;                 I                   ^  III |*    , ,.  .'
         recommended for protection of freshwater aquatic life from chronic effects is 0.0052 mg/1 free
                                                                                                          	i	
                         ...... criteripn is 0.022 rgg/1 free _cyanide. Mpre_Tecently_ developed mining-related'
                  and guidelines often specify weak acid dissociable (WAD) cyanide, largely because of the
         difiBculty in measuring free cyanide at the low concentrations of regulatory concern (Mudder and
               , 1992).  Longer-term environmental  concerns with cyanide, those not related to acute hazards
         from spills, revolve around the dissociation into toxic free cyanide of coinplexed cyanides in waste
         units and in the environment.
                   Analytical Issues
        In developing the effluent limitation guidelines for the Ore Mining and Dressing Point Source
        	Catejorj	(at 40	CFR	5311,440),	EPA	established,	a	techno|pgy-based standard for all discharges from
        	mills that use, Se,,"cyanldation" process to recover gold and sUver, and mills that use cyanide hi froth
        •iflotation	of copper, lead, zinc, and molybdenum ores.  In this process, the Agency considered several'
                                             levels hi mill wastewaters.  However, EPA found that the
                      in	both	treated	and	unfreatedjn||l	w^tewaters	were	below	the	0.4	mg/1 quantification
•        limit for	EPA-ajgroyed	test	methods	g.e.,	treatment performance could not be ievaluated^.  Because
              E and becauig complete recycling of mill waters was practiced at many facilities, the Agency
                  "	a	zero	discharge requirement. EPA was aware of specific sites where laboratory methods
                                                     4-30

           September 1994
        ! ,       "          '      '
	"	'	|'"u'"!"	''""	'"""!"|!	'"	'"!	1""1"1	'''	'''	""''	'	I1"""!	!	""'''	J!	""''	»»i«'f |h

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 EIA Guidelines for Mining	  Environmental Issues

 were effectively being used to quantify cyanide removal and suggested that these methods could be
 used by permit writers to establish cyanide limits in individual NPDES permits on a site-by-site basis.

 Analytical methods used to determine .cyanide concentrations in tailings and tailings solutions,
 effluents, and heap pore water are still being debated.  At low concentrations, testing is inaccurate
 and measurements of cyanide may not be good predictors of actual cyanide concentrations in the field.
 (Durkin, 1990; Colorado, 1992a; U.S. EPA ORD,  1993) Many complex and cumbersome analytical
 methods have been developed as a result of the need for measuring cyanide in a variety of matrices.
 Many "random" modifications of procedures also have made it very difficult to.interpret many
 analytical results (California Regional Water Quality Control Board, 1987).

 EPA's Office of Research and Development (ORD) is currently evaluating cyanide test procedures
 and methods, and is investigating a proprietary, privately developed, distillation method that appears
 to be successful for cyanide analysis.  One of ORD's activities includes revising the current methods
.for measuring and detecting cyanide fractions and eliminating interferrents.  ORD is  also reviewing
 performance data and problems of 17 currently used methods.  Future efforts will involve continued
 evaluation of cyanide species (ORD, 1993).

 Because, of the uncertainty involving cyanide forms  and analytical methods, regulatory standards and
 guidelines may not be clear on the form of cyanide  being addressed.  Nor, in many cases, do
 environmental monitoring data make clear which form or which analytical method has been used.
 This can make it difficult or impossible to evaluate  the short- or long-term potential environmental
 impacts of a proposed (or an existing) operation.  Thus, it is important that environmental
 documentation be clear as to the form of cyanide that is described and addressed, and that appropriate
 analytical methods be specified.  Similarly,  the types of cyanide complexes that are expected to occur
 in heap leach piles and tailings should be assessed, along with the rate and extent to which the
 complexes may break down to toxic forms upon their release (even in low concentrations) to
 receiving waters.                                      .

 4.2.2    POTENTIAL IMPACTS AND APPROACHES TO MITIGATION DURING ACTIVE  LIFE

 In general, cyanide can cause three major types of potential environmental impacts:  first, cyanide-
 containing ponds and ditches can present an acute hazard to wildlife and birds. Less frequently
 (because of lower cyanide concentrations), tailings ponds present similar hazards.  Second, spills can
 result in cyanide reaching surface water or groundwater and cause short-term (e.g., fish kills) or long-
 term (e.g., contamination of drinking water) impacts.  Finally, cyanide in active heaps and ponds and
 hi mining wastes—primarily heaps and dumps of spent ore and tailings  impoundments—may be
 released and present hazards to surface water or groundwater, and there may be geochemical changes
 that affect the mobility of heavy metals.  These impacts and the major issues and uncertainties
 associated with each are described briefly below.
                                             4.31                              September 1994

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::::	j	i	»,
             ICnviroitmental Issues
                                                                              EIA Guidelines for Mining
	4.2.2.1    Acute Hazards
           I                    •
        The heightened awareness of the threat to wildlife and birds presented by cyamde-containing ponds
        and, wastes have led regulatory authorities (generally, Federal land managers and States) to require
        operators to take steps either to reduce/eliminate access to cyanide solutions or to reduce cyanide
"~~—	«)iik?5iEtt!oijsin[	exposed	JSterials	to	Eelow	lethal	tevelsT	jj^jj^y"	^g^—	^	—;-—-—	—
I!.!!!!!!!!!!!!!!!!!"!!!!!!,,!!'!!!!!!!"!!!!	I	""""""!	:	llSiilii	  i',!'1'!	."i  , ''!.  .    'i"	   •   ,,•••!'  ,  • •" i  • i"! ,"   ,  •  '•„"••"    '   "» I, ' '!'  " '   ,„ ,
           ' I™"!!""' ........ ! .......................... ;""""!"" [[[ ' ...... jjyij! ............  yi'! ..... i •' i ,  i  i     i,1 ......    '   ', • •  ip  , ' •' '  i '  |!'' ,"  ,  '   ''„"'•"     '   ''" i '  'i1 "  '    i
            to the allowable concentration of cyanide in exposed process solutions are widely variable (when
           !!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!Z!!!!!!!!!!!!!!!!^                                       ...... i,,,;:;;;;;;;,;;;;;;;;;;;;;;;;;";;;;;;;;;;;;;;;;;;;;;;;;;,;;;;; ...... ;;;;;;;;;;;;;;;;;i;i;;;;;;;;:;!i;;;;;;;;;;;;;;;;;:;;
                                                             ...... ,,,,, ......                                      ,
            mm eric ..... limitations ........ are ..... established, they generally range around 50 mg/1), as are the means by which
         —         comply. '(Operators reduce access in several ways, including covering solution ponds with
   ,  	       netting or covers, using cannons and other hazing devices (e.g., decoy owls) to scare off waterfowl
            and other wildlife,	and/or	'ingtaffiig	fencing	to	preclude access	by	large	wildlife.	At	least	one	mine
            uses tanks to contain all solutions. In addition, operators	may	be	required	or	may elect	to	treat	
            tangs sures to reduce cyane concentratons, they may maintain higher fluid levels hi
            nupoundmems	so	as	to dilute	concentrations, or	they	may	reduce	the	amount of 'free	liquids	in	
            impoundments to rmnimize pond surface area. Some facilities also provide "micro-nets" over ditches

            to keep out rodents and smaller wildlife not excluded by large fences. In-evaluating the threat that
            cyanide usage at a proposed facility may pose to wildlife and birds, and the effectiveness of control
            and mitigation measures, environmental documentation should describe the standards that must be
               f   :  . '  "    i'   "':/   •   '     "I   -                          •  "    	 -      |     .
            met, the types of organisms of most concern (e.g., waterfowl  at an operation in a migratory fiyway or
            near nesting	or	staging	areas),	and	the	specific measures that will be used to reduce exposures and
          ,. nwrtgity. The grogram-by' which the measures will be evaluated for effectiveness should also be
           described; it will generally involve monitoring aid reporting deaths and supplementing existing
           methods	as	necessary.
        ,	4.2.
                  Spills and Overflows
                                                                                                       .   	!B^^^^
           Most	actual environmental nnpacts resulting from cyanide releases have been-associated" with spills
           .'--	-====	=	=
    ^l^jj^jn^jjor	failures	^^^^^^^aEu^^^^^	dam~f^u»j"i^^"irfb^p	slopes)^	]MinoFs|)ills	
           p| cyanide are not uncommon at gold facilities.  These occur typically when portions of a heap leach
           pile slumps  into a drainage ditch or solution pond and cause an overflow of cyanide-containing

           solution or when a pipe carrying pregnant or barren solution, or tailings slurry, fails or is
          "                  by mining equipment or vehicles, In all but a few major cases, cyanide spills have
                                  2? ...... §2J!5 ...... 2!°^M? ,5!S5pc?? jattenuatjkin Jn most cases. Facilities routinely
           store hypochlorite or other oxidants for use in detoxifying such spills.  In addition, some operators
       ^^^                  ...... 1^ jflitaice ...... or placed barriers between pipelines and equipment routes. Others have
           reinforced pipelines in high-risk areas.
                         ,2£s,*E?!l!Y£ ^SYF01?!6?!?,—:Serl5r?py including any water bodies—may be the most
                                          potential impacts of spills.  In all cases, environmental
                                           '   »', ,    „ '!    ,     ,,,           , ,       ',!,   ' ,„,:!' ,' , i  , •
                                        the  ractices or methods that will be used to reduce the risk of
                                                         4-32

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  EIA Guidelines for Mining	^	             Environmental Issues

  ruptures and spills, and in responding to minor and major releases.  More details would be necessary
  for operations in sensitive environments, including details on spill-prevention practices and on spill  '
  response procedures.  Particularly when cyanide facilities and structures (e.g., pipelines, heaps,
  impoundments) are near streams or wetlands, extra precautions are appropriate, including double-
  walled pipelines, additional setbacks of heaped ore or intervening barriers between heaps and solution
  ponds, automatic pump shutoffs in the event of pressure loss, etc.

  During facility operations, great attention is paid to the water balance and the efficient movement of
  solution through the system. Facilities are generally required to be able to contain at least the normal
  24-hour process solution flow and the maximum volume from the lO-year/24-hour precipitation event.
  Many States require additional capacity, sufficient to contain the flows from the lOO-year/24-hour
  event.  Because of-the size of mining operations and the large areas that can contribute flows, this can
  be an enormous volume, well beyond feasibility for many operations. Thus, most States allow an
  operation's required storage capacity to include the volume of precipitation and solution that can be
 held in heaps as well as in solution ponds and overflow ponds.  As a result, continued circulation of
 solution is necessary to ensure that heaps do not dewater and overwhelm the capacity of ponds.  Most
 States require onsite generators to ensure continued supply of electricity to pumps in the event of
 power failures.  All details of storage capacity and solution management may not be available at the
 time environmental documentation is prepared. However, conceptual plans that identify most
 components of storage capacity and the means by which capacity will be ensured usually are.

 Because miscalculations involving solution management  can be catastrophic (for example, this was a
 major problem at the Summitville mine, now proposed for the National Priorities List), reviewing
 water balance plans, even conceptual plans,  is crucial in assessing potential environmental impacts.
 This is  particularly true when operations are in or near sensitive environments.  Every aspect of water
 balance calculations should be assessed:  the amount of precipitation and runon/runofj assumed to
 occur in the designated storm event, the area of the operation that will contribute flows and the
 amount, the amount that can be held hi  each component of the water management system (e.g., the
 saturation status of a heap under normal operating conditions), even the pumping capacities of
 solution recirculation pumps.  In addition, some assessment should be made of water balances under
 conditions other than the designated storm event.  For example, spring snowmelt can .provide flows
 over several days that are more significant than long return-interval precipitation events. Similarly, a
 series of less significant storms (e.g., several 5- or 10-year events) can collectively be more
 significant than one extremely large storm.  Meteorological data are often provided hi environmental
 documentation (or hi proposed operating plans submitted to States and/or Federal land managers), and
these should be evaluated carefully to determine whether reasonable assumptions have been made
regarding hypothetical worst-case events. Also of importance is how both operators and regulators
may respond to unexpected water balance problems. In most cases, such problems are addressed as
they arise, with never a reconsideration  of the entire system and whether the original planning and
                                            4-33                              September 1994

-------
                                  thus no re-evaluation of potential environmental impacts. It may be
            appropriate in some cases to require more formal contingency planning at the outset, with a
            reassessmenl of potential envu-onmental impacts required when critical components of the "water
            4.2.2.3    Liner and Containment Leakage
                                             ^                                         ,.
          	j,          ii  ,.    	;	;	;	-	;	.•;	••'   . [ _' , '	
            As described in Chapter 3, heap leach operations use liner systems of various sorts under heaps and
            solution poods.  Ih'general, liner systems consist of a prepared foundation (compacted subsurface,
            with large rocks and objects removed), a bedding layer (if used), synthetic or clay liner, seepage
            collection/detection layer (if used), and a cover layer of material to protect the liner.  Perhaps the
            single most important factor in preserving the integrity of liner systems is their proper installation,
            including comprehensive construction QA/QC. The type of liner system that is used generally is
           based on site conditions, operator preference, and regulatory requirements (Van Zyl, 1991).  Liners
           are usually of polyvinyl chloride (PVC) or high density polyethylene (HDPE); recently, very low
           density polyethylene (VLDPE) liners have emerged. Although there now is ultraviolet-resistant PVC,
           there have been some problems with older PVC liners degrading when pond or ditch liners are
           exposed to ultraviolet light.  In most cases where there have been significant liner failures, they have
           been due to improper installation or accidents combined with inadequate construction QA/QC.
           There, is a clear economic incentive to Tnimmfae pregnant solution loss during operations; this is often
           cited as a reason why operators' design plans should be accepted as proposed. In practice, operators
           assess the optimum balance of economic and environmental considerations in design planning.  Thus,
           the,	costs	of actual	containment	technologies and'practices are balanced with th* economic losses
           associated with a certain amount of solution loss as w«n as regulatory and esyirocmental
           considerations.	As	noted	in	Chapter 3, regulatory authorities (Federal land managers and States) are
           increasingly requiring solution .ponds to be doobie-iioed, often with a composite liner system that
 1          includes'	leak detection/collection.	Requirements far heaps more often  specify"	single	liners,	which	
        _   may be	synthetic or clay. In southern' California, for example, the 'great depth to groundwater and
	the artramafinn capacity of soils ted the Regional Watec Quaiiy Control Board to specify single liners
           fbrbeapc.
               j            • '   . "•':  '"'• , 	 '                     •     •  •          '••;•.[••
           In many locations, however, heaps are located entirely or partially in drainagewayc (generally
           ephemeral) over shallow alluvial or shallow bedrock aquifers. This is usually the.case for tailings
       "    impoundments, but"these are infrequently lined; seepage through and under dams is generally
           collected in toe ponds* but some seepage may bypass such ponds.  Should leaks occur through heap
           liners or should seepage bypass collection ponds, cyanide can reach the alluvium and/or shallow
           groundwater.	This	can	then affect downgradient surface waters or springs or can reach -bedrock
          ILii	iii!iiiiiiiiiiiiiiiiiiiiiiiii,iii!iiaiim                        i       i        II  I  i     I    M                   P          i i
           aquifers. Whether subsurface materials can attenuate any such leaks and reduce cyanide levels
           depends on the nature of the materials and the location and extent of water present in the subsurface.
          	t	I	j	i	i	i	i	I	[i i ij j	ii 11	...i	i	•	|i 111	i	•	in	i	
                                                        4.34                             September 1994

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  EIA Guidelines for Mining      	           .	Environmental Issues

  Evaluating the likelihood and the potential consequences of cyanide leaks is particularly dependent on
  detailed information on the subsurface and on proposed liner systems, and on construction QA/QC.
  Subsurface information of concern includes the nature and characteristics of the material (depth,
  mineral composition, compressibility, shear strength, seasonal saturation levels, presence of springs,
  etc.) Liner systems should be fully described, along with a clear justification for then- selection (e.g.,
  why PVC over VLDPE, why flexibility was or was not important,  why and how their resistance to
  sunlight/punctures was considered, etc.).  Detailed design and QA information is often not provided
  in great detail, but in some cases may be necessary.  Information on the minimum standards that are
 • imposed by applicable regulatory authorities can assist in determining if more detailed information is
  needed—if standards are very general, then more information may be appropriate, for example.

  Should a proposed operation be located in an environment where leakage could be especially
  damaging, specific information on the subsurface, on site preparation, and on the liner system and
  installation and construction QA/QC are always necessary for an evaluation of potential impacts.
 Finally, the presence or absence of comprehensive monitoring programs (for example, monitoring of
 seepage detection/collection systems, if any; of bedrock and alluvial groundwater, of materials and
 pore water in heaps or impoundments themselves; of solution and slurries; of dam/heap stability; of
 the integrity of containment devices, etc.) and commitments to 'respond to unexpected events can be a
 significant determinant in the level of information needed. A sustained monitoring program,
 combined with financial commitments and/or regulatory guarantees that environmentally appropriate
 responses will be taken if necessary, can provide significant assurances that long-term impacts will be
 minimized, even in the absence of detailed information and analyses.

 4.2.3   CLOSURE/RECLAMATION AND LONG-TERM IMPACTS

 4.23.1    Closure and Reclamation

 Until the recent past, reclamation (if required) commenced immediately upon cessation of operations.
 With increasing concern over environmental .quality in general and toxic pollutants specifically hi
 recent decades, however, the concept of pre-reclamation closure has  received more attention by States
 and Federal land managers.  However, relatively few cyanide operations have been completely
 reclaimed to date, since large-scale cyanidation operations are a phenomenon of recent vintage.
 Consequently, closure and reclamation measures are not yet well  established.

 Closure entails those activities conducted after a cyanide unit ceases operating in order to prepare the
 site for reclamation.  Closure essentially consists of those activities that are required to remove  a
hazard or undesirable component, whether it be chemical or physical, to the extent required by States
 or Federal land managers. It can entail detoxification/neutralization of wastes, treatment and/or
evaporation of rinse liquids and pond water, dismantling associated equipment  and piping, removal or
treatment of waste, reconstruction, grading or stabilizing, and/or chemical testing.
                                            4-35                              September 1994

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              Environmental Issues
                                                                       EIA Guidelines for Mining
              Reclamation consists of those activities that are undertaken to return the site to a condition, suitable for
              the future uses specified by the State or land manager. Reclamation may involve regrading;
              backfilling ponds; removal of wastes; site drainage control such as diversions, channels, riprap, and
              collection basins; perforating liners to allow drainage through heaps; capping to reduce infiltration
            '    I            . . •     ,                        ..          ". rk .   .  •   ,  ft, '.       |          '       .   .
              and/or to provide a substrate for revegetation; and revegetation to establish ground cover and protect
              against erosion.                                                                -

             4333    Long-term Environmental Concerns and Issues

             The principal concerns with closure of spent ore and tailings impoundments are long-term structural
             stability and potential to leach contaminants.  Structural stability is dependent on the physical
             characteristics of the waste material (e.g., percent slimes vs. sands in impoundments),  the physical
    11 in iiiiii 1111111
    i iiiiiiiiiiiiiiiiiiiii
 configuration of the waste unit, and site conditions (e.g., timing and nature of precipitation, upstream/
 uphill area that will provide inflows). The potential to leach contaminants is largely dependent on site
      tions, including reclamation and mmeral(s) geochemistry
   III III III lllllll 1111111111111
111	•	I	Ill	Ill
 Cyanide is not the only contaminant mat is present hi tailings effluents or heaps; numerous other
 constituents may be present in the waste material and present potential problems following closure and
 reclamation. Nitrate (from cyanide degradation) and heavy metal (from trace heavy metal sulfides in
 the ore) migration are examples of other significant problems that can be faced at closure of cyanide
 operations.  As noted above, testing and analysis of cyanide is a major issue because it is difficult to
 obtain consistent and reliable test results.  Another significant concern is the generation of acid
                 i                   iii                            .11
 drainage, typically caused by the presence of iron sulfides that break down to form sulfuric acid.
ill (•	lililillilllll  	IIH^        	1H        iiiliill	        '	i 	i	                     •	!	'
 Because of the great variability among cyanide operations, including ore characteristics and climatic
 conditions, adequate characterization of wastes and materials is an important consideration for site
 closure and reclamation. In part because few have been closed/reclaimed, there is limited information
    I            I                                                    H.J: ..       |,   ; „ '.    ' .•      i,'; •' ,
 available on the mobility of cyanide and cyanide complexes in closed and/or reclaimed heaps and .
 +4*Im«V*1' i I'm >"> Itll • >V7»» 1 ^ l»l n  US^*«*AWAW  «*+ n •"••-raaanl O ««4l* TXol^^A^. «±A«_  _ • -.	*- _  ,_.__ _.fAl__ J_-	1 _.*.?	
            tailings impoundments. However, at several South Dakota sites, nitrate, one of the degradation
            products of cyanide, has been detected in areas beyond the heap . Operators were able .to meet the
            0.2 mg/1 cyanide detoxification criteria, but elevated levels of nitrate have prevented the attainment of
            other criteria developed by the State for the site.  The nitrate levels in surface runoff from the mine  .
            sites have exceeded treatment criteria and low levels of nitrate have been detected in downgradient
            wells.  (purMn, 1990)
   ,
            In addition, the chemistry of a spent heap or tailings impoundment may change over time.  Although
            effluent samples at closure/reclamation may meet State requirements, the effluent characteristics may


                                      °
            Modeling can be performed to assess the long-term geochemical conditions at the site taking into


-------
 EIA Guidelines for Mining  	   Environmental Issues

 consideration the chemistry of a spent heap over time, and be used to design closure and reclamation
 plans. Factors affecting chemical changes in a heap or tailings impoundment include pH, moisture,
 mobility, and geochemical stability of the material.

 In addition to high cyanide concentrations, the post-leach solution (pre-cyanide treatment) at heap
 leach operations is likely to have the following characteristics (Mudder and Smith (1992):

      •  HighpH(9.5tolls.u.) .           .

      •  Moderate to high dissolved species, mainly  sodium, calcium (from added lime), and sulfate.

      •  Potentially elevated metals of ionic-forming complexes such as arsenic, molybdenum, and
         selenium'     .                            .

      •  Potentially elevated metals which form soluble metallo-cyanide complexes such as iron,
         copper, mercury, cadmfr"ft,  and zinc.           •

Rinsing spent ore for detoxification typically takes from several weeks to several months; however, hi
some cases a site may require several rounds of rinsing in .order to meet State or Federal standards.
One problem that frequently has been encountered is that rinsing/treatment is conducted and effluent
standards may be met, but subsequent rinsing or testing reveals increased cyanide and other
constituent concentrations. (Nevada, 1993b) Spring snowmelt also has.caused effluent concentrations
to rise. Several States, as well as the Bureau of Land Management, now request follow-up  effluent
sampling after periods of rest or after rainy season/spring snowmelt prior to approving completion of
detoxification.  (BLM, 1992; Idaho, 1993, South Dakota, 1993)  Although the reasons for incomplete
or variable rinsing have  not been confirmed, Durkin (1990) suggests that non-uniform neutralization
or dilution may be factors. A number of facilities have had to switch treatment methods after a
chosen method failed to  reach the desired concentrations. Thus, in practice, rinsing may take many
seasons, or years, to complete.

Agglomerated heaps are more difficult to rinse because aggregating the material prior to leaching
(with lime or cement or other materials) keeps the pH elevated, which  in turn makes reduction of pH
and detoxification of cyanide more difficult. One Nevada mine (Trinity), for example, operated an
agglomerated heap;  when leaching ended, initial WAD cyanide concentrations were 400 - 500 mg/1
and the facility proposed using natural degradation to reduce the cyanide concentrations but continued
high pH has prevented mis from being effective (Nevada, 1993c). As a result of this and many other
site-specific circumstances that affect detoxification success, State-granted variances from rinsing
criteria are not uncommon in many States.

One mine in Nevada encountered a major problem during rinsing of a spent heap. While .
recirculating the solution during leaching, gold was removed from the pregnant solution but other
                                             4.37                              September 1994

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 I n1             I    i        I"   i II           i            '      i           '     ', "i   I    "IN      i'M     ii

               I            '.                '                             .         '    I
	'	'«">	'	Environmental Issues .        	            EIA Guidelines for Mining
           metals and constituents continued to accumulate and were not removed from the solution.  As a
           result, during rinsing, the mercury levels in me rinse water rose to 4.0 mg/1, three orders of
           magnitude higher man the primary drinking water standard of 0.002 mg/1.  The tremendous amount
           of water required for consecutive rinses in order to reach the 0.2 mg/1 cyanide standards has also
    1  •     been ...... an ..... issue jn ...... Nevada,' (Nevada, 1993b)   "                                •'        '
                           '' i    I                                   .
           Severa| ...... mines ....... in ...... five ...... w^estern ..... states ...... have. ...... experienced elevated selenium levels (Altringer, 1991).  The
           Bureau of Mines is investigating the use of biological and chemical reduction of selenium in cyanide
    ||||||||| ^     UJ illilllta        ...... ' [[[                                       [[[ .................................. J .....................................
           tailings pond water. Although high costs may make the treatment prohibitive, the research study was
           siicceisfiil ...... in ...... reducing ..... selemum ...... concentrations ...... in ..... tfiejaboratpiy from up to 30 ppm selenium to 0.02
    PII111 iipiiiii ppm.                                    ,  •

           Water balance is a major concern at some sites.  In arid regions, with limited water resources,  the
          amount of water that isiiinecessary-to rinse heaps to a required' standard may be" a significant concern.
          Conyeisejy, ....... in wet ...... climates ....... tike ...... South ...... Carolina, excess water from heavy precipitation and/or
          snowmelt can place a strain on system operations and may make draining or revegetating a heap or
                      ......    .....      - .....     - .........     - ...................... • ........................... • ........ [[[ • .......... - .............. ............................................ [[[

               1  ,       . .  .    .                     •                         ..!•...
          Another potential problemjnay	be	caused by	"btijod-offe,^ Jess p_enneable lenses or isolated .areas of a.
          heap that affect percolation and low throu^hi the heap, leading to preferential paths for fluid
          migration.  Available research data'suggest that preferential flow paths and blind-offs increase with
          time and volume of liquid. These preferential flow paths can limit the effectiveness of
          treatmo^neatralization and may leave pockets of contaminant,* behind in a heap during closure,
          which men have the potential to leach out after reclamation.
               i  	      M'l1      (          ^ ^          	' 	•	(''	:       .       •     .
    	Acid	generation	also^may be a major problem facing many	nunes^	At	one itime, acid generation at
    II^ZJpy^Qide sites was not considered to be a potential problem as many mining facilities used only oxide
         ores" (not suffide ores). However, cyanide leaching facilities that mined predominantly oxide ores
         have reported cases of acid generation. Even tailings mat were originally alkaline have subsequently
         „_	:i	j -_;j ~-!t!--~i*     Aiii.   *- *•       *_    ,«.«.'''  '    	  '      "       •
                    \. acia generation.  Aitnouen lime mav be added during cyanide leaching, with residuals
                           °r agglonierated heaps, the time component may eventually wash away through
         weathering, leaving sulfide compounds to form acid drainage.  (Ritcey, 1989; Catifomia, 1993b)  As

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 EIA Guidelines for Mining                                              Environmental Issues

 many complexities with detoxification and reclamation and which .if any difficulties will be
 encountered are seldom known at the time that the potential environmental impacts of a proposed
 mining operation are evaluated.  As a result, environmental documentation should describe
 contingency plans for overcoming possible difficulties and potential impacts under these conditions.

 If detoxification is successful, most residual cyanide hi closed heaps and impoundments will be
 strongly complexed with iron.  Although the stability of such complexes over long periods is not well
 understood, cyanide is generally  considered to be much less of a long-term problem than acid
 generation, metals mobility, and  stability (which are discussed elsewhere). Thus, evaluating the
 potential post-operational environmental impacts associated with cyanide in heaps, spent ore dumps,
 and tailings would involve assessing the means by which operators will ensure that cyanide and its
 breakdown products and metallic complexes are contained and reduced to environmentally benign
 levels prior to site abandonment.  It also may involve an assessment of the ability and authority of
 applicable regulatory authorities to guarantee this.  Conceptual plans for operators who will detoxify
 and reclaim heaps and tailings are generally available at the time environmental impact assessments
 are performed, but not the details. This may be sufficient, given that cyanide may not be an
 important environmental issue over the long term.  What is important is that the plans describe not
 only what is anticipated to occur  at closure and reclamation (e.g., continued recycling of rinse water
 until WAD cyanide levels reach regulatory standards) but also the implications for long-term
 environmental performance .that potential difficulties and changes in plans could have.

 4.3    STRUCTURAL STABILITY OF TAILINGS IMPOUNDMENTS

 The most common method of tailings disposal is placement of tailings slurry in impoundments formed
 behind raised embankments. Modem tailings impoundments are engineered structures which serve
 the dual functions of permanent disposal of the tailings and conservation of water for use in the mine
 and mill.  Impoundments are often favored over other tailings disposal methods (e.g., tailings piles,
 mine backfilling) because, among other things, they are "economically attractive and relatively easy to
 operate" (Environment Canada, 1987). Such economy derives in part from the fact that tailings and
 waste rock may account for a major part of the embankment construction materials. Additionally, the
 phased nature of embankment construction spreads the  capital expense of disposal unit construction
 over the life of the project, reducing initial capital outlays.  Section 3.2.6.2 discusses the types of
'tailings impoundments .used and then* construction methods.

 The disposal of tailings behind  earthen dams and embankments raises a number of concerns related to
 the stability and environmental  performance of the units. In particular, tailings impoundments are
 nearly always accompanied by unavoidable and often necessary seepage of mill effluent through or
 beneath the dam structure.  Such  seepage results from the uncontrolled percolation of stored water
 downward through foundation materials or through the embankment as well as the controlled release
 of water in order to maintain embankment stability. Impoundment seepage raises the  prospect of


                                            4.39                              September 1994

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            I

          Eiy
             vironmental Issues
EIA Guidelines for Mining
il'STi'iSS	B surface water and groundwater contamination and, coupled with the potential for acid rock drainage
          (see above), may necessitate long-term water treatment well after the active life of the facility has
 11111	      passed. Moreover, failure to rngfatain hydrostatic pressure within and behind the embankment below
  •        critical levels may result in partial or complete failure of the structure, causing releases of tailings and
                        i     ii                                                       i
          contained mill effluent to surrounding areas.
         '   i             i   /
       .  Therefore, the challenge posed by raised embankment tailings impoundments is achieving a balance
          between cost, stability, and environmental performance objectives.  Because raised embankments
          evolve over the life of the project they present the need and the opportunity to reevaluate design
       "   parameters Id address changing conditions and project objectives over time. The evolving nature of
          raised embankments also means that finished impoundments often differ substantially from their initial
    ™" """"	pitas!	^ccoxdrngfyTit	can"	Be	very"	|i§£i5o".deteiS^ in advance the potential for environmental
          difficulties or the need for environmental  controls:
ii iiiniiniii1
lilI'llllilK
                                             in in in n I in nil i ill in Iii i iln i in in n
          4.3.1   SEEPAGE AND STABILITY
     lilililllii   •  (iii	nil i	i ii	i	ii|i|ili	ii	niii	
          i  I          i  '    "n    ii                .                   I-
          In general, tailings impoundments and the embankments .that confine them are designed using
          information on tailings characteristics, available construction materials, site specific factors (such as
          topography, geology, hydrology and seismicity) and costs, with dynamic interplay between these

         factors' influencing the location (or siting) and actual design of the impoundment.
         The three methods of embankment construction (upstream, downstream, and centerline) differ with
         respect to the quantity of materials required for construction and the types of operational and designed
         controls that	may be incorporated	into the structures for stability and environmental performance.
         For fn
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 3SIA Guidelines for Mining 	•	        Environmental Issues

 permeable layers of the foundation may result in piping or exceedence of soil shear strength, causing
 foundation subsidence and compromising the stability of the overlying embankment.

 The .phreatic surface is the level of saturation in the impoundment and embankment (the surface along
 which pressure in the fluid equals atmospheric pressure (CANMET, 1977)); in natural systems it is
 often called the water table.  Factors that affect the phreatic surface in the embankment include the
 depositional characteristics of the tailings (permeability, compressibility, grading, pulp density, etc.)
 and site-specific features such as foundation characteristics and the hydrology and hydrogeology of the,
 impoundment area and its upstream catchment area. Changes to the phreatic surface can be caused
 by: malfunction of drainage systems, freezing of surface layers on the downstream slope of the dam,
 changes in construction method (including the characteristics of the placed material), and changes in
 die elevation of the pond.  The level of the water table also may be altered by changes in the
 permeability of the underlying foundation material; sometimes these are caused by strains and
 subsidence induced by the weight of the impounded tailings (Vick, 1990).

 Impoundment design must provide for a cost-effective and reliable containment system.  Choices
 regarding  materials, slope angles, drainage control, raising rates, etc., all  affect the cost as well as
 the stability of the structure.  Therefore, stability analysis is performed to optimize the structure with
 respect to cost and other objectives while maintaining reliability.

 Slope stability analysis begins with an estimation of the reliability of the trial embankment.
 Typically,  the embankment designer proposes the internal and external geometry of the trial
 embankment and then calculates the safety factor of the design. Using detailed information on the
physical properties of the fill material and estimates of the volume of tailings and water to be
contained in the impoundment, the phreatic surface is predicted.  The designer then examines a wide
range of failure modes to calculate the estimated stresses expressed at hypothetical failure surfaces.
The safety factor for each failure mode is then calculated by dividing the estimated resistance of the
embankment to stress along the failure surface by the stress load expressed at the failure surface.
With this process the designer can look at changes in design parameters and the resulting influence of
the safety factor to arrive at the least-cost option consistent with safety objectives (Inyang, 1993).

The major  design precept is that the phreatic surface should not emerge from .the embankment and
should be as low as possible near the embankment face (Vick, 1990).  The primary method of
maintaining a low phreatic surface near the embankment face is to increase the relative permeability
(or hydraulic conductivity) of the embankment in the direction of flow. This is accomplished by
using progressively coarser material from upstream (Le., the tailings side) to downstream and/or by
incorporating drainage features (e.g.", chimneys drains, blanket drains) in the dam itself to keep fluids
away from the downstream face.  Tailings slimes, clays, and/or synthetic liners (rarely) may be used
to reduce permeability of the  upstream face.
                                             4-41                              September 1994

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                                   I
                I           ' '

~i^==EnyifoiimeBialfesaes	'      	EIA Guidelines for Muring



             Other means that, in various combinations, are used to maintain a low phreatic surface near the dam

             include:
                I          I                I            y                          i                 .        i


                  •   Reducing the water content of tailings by dewatering prior to disposal.


             ,     *   Reducing groundwater infiltration into the tailings. This can be a serious problem, at least
                      seasonally, when tailings impoundments are placed over alluvial materials.  Infiltration can
	i	of ..reduped	by preparing the ground surface in the impoundment-area:  "lining" with
                        L   ^j native gojig and fa^ imported clays, or even synthetic liners, and possibly
                              r n^^inc* im^A^ ffcAPa l*na«*r> +*% nfvmvaetT +1+e** «M>«%»v«*«3***«*,A«	»		At_ :*_t_ _ ^_«*» . _

                     including drains under these liners to convey the'^roundwater underneath the tailings.
                     Incorporating drains underneath and through the dam to ensure that any seepage/drainage is
                     controlled.  This can include incorporating'filters orjlter zo^^upstream of drams to help
                     prevent clbgfmg^ hence maintain differences in r«rmeabiiity across zones.  Filter zones
                     may be constructed of graded sands or synthetic filter fabrics (Vick, 1990).
                            "                                     '                             '
^E	II1III.	In ill	*	s:	il^SSSiSSi	?§	IM?	!*??,	w**?r	Ii	toe	impoundment as possible by recycling water to the
  i           ,       mil or by"decanting water aid pumping it.to an alternative fines settling and water storage

111111111111111' 11 llllllllll 11 lllllf Illlllllllllliiili III 111 111 1111111111 111 I IP' I II ill           i                IT          ii                             I
                                                      i mi n n iii i nnllllnillini i linn nnnnnnnnn iiiini inn mi inn n i n i n inn nn nnillllnn i in win inn i in mi inn 11 11 niiii|iiiiiil ill inn i mi linn  nil inn in|i 11 n n niilinnnnnn inn inn 11 n n inn mi inn n nil in inn n in i n 11 i i inn 11 n
             i ii in iiiiiii n iiii inn in iiiiiii i iiiiiiiiii iiiiiiiiiiiiiiiiiii|iiiiiiiiiiiiiiin i immmmimimm m««m immmmmmmimm minim immmmmmmmmiimmmimm      iiiiiiiiiiiiiiiiiiiiiiiini in nil n i n iiiini iiiiiiiiiiiiiiiini i nun iiiiiiiiiiiiiiini iiiiiii iii n i inn iiiiiiiiiiiiiiiiiiiiiiiiiiiii mini i mini inn pi iiiiiiiiin|iiiiiiiiiiiiiiinn iii i mini  ««««««inn «i|iiiiiii««««««««« minimi in nil mi inn niiiiiiiiiniinnnin i n n i i inn 11 n
                 *   Maintaining free water as far behind the crest of the dam (i.e., as high in the catchment) as
                    possible by sloping the surface of the tailings upstream away from the dam.
         •  	ii'i'iji!	iiii	iiv    	ii •        •	         '    •
    	I	S	Allowing	fluids	to	escape	into	the	subsurface.	This.is generally not an option since States
    	!   k generally impose strict groundwater protection •*•«'»•««« •                       . •
                *   Diverting runon away from and around the impoundment and dam. This is accomplished
     •iiiiiii	iiiiiiiiiiiii: mi	iiiii'i i!	!	with benns and other water diversion techniques.
                              	i	;	r	 I	•	

                                                             PERFORMANCE
                             ,       ,          ,                        . .....    .
          The selection of any of these approaches to embankment design has implications for the operational
              long-term environmental performance of the impoundment system.  For example, incorporation

                                                      ...... £ ...... SlSE-IEE £«ssure ,H!*i? ,*?. 45m provides a
                          ,   .....               ,        ......  ......      -              ,      ,.
                     ..... Sease ofcomamjnatgd_ ...... Iuids: ............... UiSer, ..... existing ^JDES effluent guidelines, such releases
          typically wffl require collection and return to the injwundrnent smce discharges are prohibited from

         ' .....                                                             a iiner l° prevent downward
                   , °f P°Uutants to shallow groundwater. Embankment drainage systems also create a post-

                               ...... SSSffii .............       ..... SB ..... fP*0"041116111 fe fey *«ign not impermeable,
          contaminated effluent, possibly including acid rock drainage, may be released from the impoundment
          ^kr tp6 active life of the project. If the active pump-back system for the toe pond is no longer in
          operation, such effluent may be released to area surface water.  Accordingly, treatment-in-perpetuity
          or some alternative passive treatment or containment method may be necessary to prevent surface
          water releases.

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 EIA Guidelines for Mining                                               Environmental Issues

 Another trade-off between stability and environmental performance is the incorporation of liners.  In
 areas of shallow alluvial groundwater,' liners may be necessary to prevent intrusion of water into the
 impoundment.  However, such liners will simultaneously increase the retention of impounded water
 behind the dam and reduce dam stability, all else being equal. On the other hand, the absence of a
 liner may increase the downward migration of impoundment constituents to shallow groundwater.

 Surface water controls may be of particular importance in post-closure stability considerations.  .
 Surface water runoff diversions are generally employed to limit the intrusion of excessive amounts of
 water into the impoundment, which reduces dam stability and prevents drying of tailings. Failure.of
 surface water controls after impoundment closure could result in an increase hi pore water pressure
 within the impoundment, threatening the stability of the embankment. In general, active measures to
 control surface water runon and runoff during the operative Me of the project may require alternative
 methods or long-term management after closure.

 4.4    NATURAL RESOURCES AND LAND USES

 The act of mining can result in major changes to all natural resources on and hi the vicinity  of the
 mine.  This section describes several major natural resource systems that may  potentially be impacted
 and the types of impacts mat may occur.

4.4.1    GROUNDWATER              .

The potential impacts to the groundwater resources hi the area of a mine are similar to those that can
 impact surface water quality. Acidic water from mine drainage, metals, cyanides, or other toxics
from the mining operation may enter groundwater in the vicinity of the mine.  Elevated pollutant
levels can contaminate drinking water supply wells.- Disturbance hi groundwater flow regime may
also affect the quantities of water available for other local uses. Further, the groundwater may
recharge surface water downgradient of the mine, through contributions to base flow hi a stream
channel or springs.  Conversely, surface water affected by mining operations can recharge
groundwater, particularly alluvial aquifers.

An assessment of potential groundwater impacts requires that the baseline groundwater resources hi
the area of the mine be completely characterized, including descriptions of the aquifers (bedrock and
alluvial systems), aquifer characteristics, flow regime (an understanding of the potentiometric surface
for each aquifer), springs, and background groundwater quality.  At least two years of groundwater
quality data are generally needed (or an alternative interval that is sufficiently representative  of likely
variabilities hi groundwater quality).  The collection of baseline groundwater data should be  described
 in study plans that ensure that useable data is being collected.   The collection of these data usually
 requires the installation of a groundwater monitoring network of wells.  Where wells are installed,
                                             4.43                             September 1994

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                                            iiiiliii iiiinili in	IIIM^^^               iiiiiw^                        	iiiiiH^^^^
              liiTironmental Issues
EIA Guidelines for Mining
              documentation should describe the location, depth, construction/completion data, and sampling and
              analytical methods.               •                             .                  ,

                                "'   '                                    !                  i,"   •    .
              In addition, to the baseline characterization of the groundwater in the project area, the following
              information is generally needed to allow an assessment of potential impacts on groundwater resources:
 : ="iL'iES ..... ::<::< i::: ' i i:::1:::    . [[[ ' ...... ' [[[                                                  ' ............................................ I [[[ '

 ' ..................... •'|'"'1' '"'"" 'l|"'1" "'""' ' !lj ................... '" •"" Location and construction design plans for toxic materials storage areas (cyanide, oil, etc.),
                       waste management units (focusing on impoundments), leach units, solution transport
                       ditches, process ponds, and surface and underground workings.  These should be reviewed
                       in conjunction with hydrogeologic data (particularly the potentiometric surface for each
                       aquifer in the area of the proposed units).  Any practices to be used to protect groundwater
                       resources  (liners, grouting, etc.) .should be examined closely.
            wiS    •   Acid ...... generation potential for the waste rock, tailings, and the mine workings.
                                                     :	.waste,	.rock	and,	ore	to	defennine	what,	metals,	and	gther	,	:	-	;	•	
                                        present and avalable for	!	
                  •   If the rock has a net acid generation potential, mitigation measures should be outlined.
           Iv'ilIF1'!1!            -        '  ' 	.               i    .,	                             .   	

                L.Y.ILocations of and information on any local residential wells or well fields and an evaluation
S™lj««S,;™"j,^S«Sf howtii^y may be .impacted by the new source (both in terms of quantity and quality)
            '                             "
                      Where there is a hydraulic connection between ground and surface water, an analysis of
                      how potentially affected groundwater could affect surface water flow and quality (and vice
                      yersa),;> When dewatering can create a significant cone of depression and affect the
                                 of gjomid water/or surface water recharge (see section 3.L4.1), mfbrmation on
                      both short- and long-term effects would be necessary.
                                          111 Illllllllll lilllllB II III llllill I III II 111 111 !ll 111 111 lllllll 1111 111 111 II1) ill 111 III II 111 1 III) i III llllllill III Illlill 1 111
                SSES	SlBlMpg » such that h causes massive land disturbances.  These disturbances hi turn can
                 IS® major types of impacts on aquatic resources, including aquatic life. The first type of impact
            would result from die contribution of eroded soil and ngterial to streams	and water bgdies (see
    .    ' I Sli^jji	"JM	|§	g°i|	iE-please"	of poJJ^1""^^1»——	^^	-—.««..-. —-	—	«m^  ^

 	'	°  6™  streams; wetlands   r
            other,	water	bodies.	IJeinpjMrary	disruptions	would	occur,	from	road,	construction.	and	similar activities.

            Permanent impacts would be caused by actual mining of the area or by placement of refuse, tailings,

            or waste rock directly in the drainageway—more often than not* this is in the upper headwaters of

            intermittent or ephemeral streams.  (Both types of activities are subject to §404 of the Clean Water
            Act—see section 6.1.)

                             	                    '               	     -   it.        i	                  in
           III II  III  lllllll 111 iiilllil nil llllllill lllllll llllH^  lilllllll illllilli 111 lull illllil ill ill i lllllli 11 lllllll ill llllllill 1111	Ill llllllill Illllllllll 1" I ill 111)) HI 111	Illllllllll 111 ill 111 I Illllllllll 11  Illllllllll III I |i|||l||||ll|i|lll|l||il||illl|llllllil -

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  UA Guidelines for Mining	^^	   Environmental Issues

  Means to prevent future impacts, from the release of pollutants to surface waters from waste materials
  or from mine workings should be addressed in a reclamation plan, and effective reclamation can
  provide substantial mitigation. As is noted elsewhere, however, reclamation plans for metal mines
  are often only conceptual at the time of mine permitting. Thus, preparers and reviewers of EAs and
  EISs often must rely on applicable reclamation requirements and on the processes that are in place to
  ensure that reclamation planning proceeds according to those requirements.

  For impact assessment purposes, aquatic life is generally defined as fish and benthic
  macroinvertebrates; however, phytoplankton and other life forms may also be considered, depending
  on the type of aquatic habitat and the nature of impacts being assessed.

  Impacts to  relative abundance or biological diversity may occur as a result of chemical and physical
  changes or from direct removal or introduction of species.

 A detailed discussion of the many approaches and methodologies that may be used to define and
. monitor aquatic resources is beyond the scope of this document. However, there are numerous
 reference documents that can be used in assessing the environmental impacts to aquatic life associated
 with a proposed action. Several examples include:

      Harrelson, C.C., C.L. Rawlins, and J.P. Potyondy. 1994.  Stream Channel Reference Sites:
      An Illustrated Glide to Field Technique.  U.S. Department of Agriculture, U.S. Forest Service,
      Fort Collins, Colorado.

      Platts, W.S., W.F. Megahan,  and G.W. Minshall.  1983. Methods for Evaluating Stream,
      Riparian, andBiotic Conditions. -General Technical Report INT-138.  U.S. Department of
      Agriculture, U.S. Forest Service, Ogden, Utah.

      U.S. Environmental Protection Agency. 1989. Ecological Assessment of Hazardous Waste
      Sites:  A Field and Laboratory Reference.  EPA/600/3-89/013.   •

      U.S. Environmental Protection Agency. 1989. Rapid Bioassessment Protocols for  Use in
      Streams and Rivers: Benthic Macroinvertebrates and Fish. EPA/440/4-89/001.

     U.S. Environmental Protection Agency. 1993. Habitat Evaluation:  Guidance for the Review
     of Environmental Impact Assessment Documents.

The impacts of a proposed action on aquatic resources can be  either beneficial or adverse.  It also
may vary significantly, depending on the species. For example, increases in stream flow may
preclude habitation of certain species of macroinvertebrates and/or fish but, at the same time, may
also provide new habitat for other species  of aquatic life.  Too often, impact assessment is based on
single species management.  A more productive approach is to consider the entire ecosystem.
Whether the analysis considers the entire ecosystem or an individual species, endpoints/criteria must
                                            4-45                              September 1994

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             Environmental Issues
                                                                     EIA Guidelines for Mining

    ! IIW	f f!!1'
llllllH
 be established by which the impacts of the project will be evaluated. Assessment endpoints are
 enyironmental characteristics which, if they were found to be significantly affected, would indicate a
 nee||
 regulated species of macroinvertebrate may not be directly considered a valuable species but it could
be an important component of the food chain and local ecosystem which contains other valuable
               l	5£'ajJ5|>osed	action	on	aquatic	life	can most effectively be determined insufficient
           baseline data are available.  In general, baseline aquatic life studies of one or more years reflecting
                    	nxujtipje	seasons	(«.g.,	spring,	,2222;	fall)	are-needed	to	adequately describe reference
                      	'Annual	ancVseasonal	variation m	.aquatic life g|rolations (especiaiy macroinvertebrates)
              ; normal.Without	adequate baseline data, it is not possible to measure if changes in abundance
                                                tion°afc from anthropogenic activities (e.g., mining).
                                          should be obtained directly from the drainage to be affected by the
               ]	Jhfcfarfe	not	feasible,	background data should be collected from'an,,iinimpacted
               " ecosystem (e.g., reference site) with similar characteristics to the proposed impact area. (In
                                            been	degraded ^ historic mining (or other) activity.  There, it
                  
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  EIA Guidelines for Mining	                 Environmental Issues

  the primary purpose of a study is to determine the presence of a threatened or endangered fish
  species, for example, it would be inappropriate to use rotenone, which has a 100 percent mortality
  rate.  The references cited above provide guidance on method selection and use (both for baseline and
  long-term monitoring). In addition, the potential presence and effect of metals such as mercury Or
  selenium that are bioaccumuiated should be addressed.

 An important variable that the operator and the reviewer should consider in aquatic resource
 assessments is the duration and extent of the proposed impacts.  For example, if the proposed action
 {or potential alternatives) will temporarily decrease stream flow during one season, the impacts on
 aquatic resources would be expected to be different than if the activity will lead to long-term effects
 (including post-mining conditions). The related indirect impacts of the activity should also be
 evaluated.  For example, if development of a proposed mining operation provides access to an
 otherwise inaccessible land/drainage area, the potential affects of non-mining related human activity
 (e.g., recreation) should be considered.  Another important consideration in an historically mined area
 would be me cumulative impacts of the proposed operation. Thus, the fact that the area to be mined
 was degraded from past mining activity  would not eliminate the need for a full-scale assessment of the
 cumulative impacts of mining (and other) activities on the aquatic resources and of the incremental
 impacts of the proposed operation.

 4.43  •  WILDLIFE

 Similar to aquatic resource evaluations, numerous references are available to assist hi evaluating
 potential impacts on wildlife or in evaluating data and studies that are submitted by applicants.
 Several examples include:

      U.S. Environmental Protection Agency.  1993.  Habitat Evaluation: Guidance for the Review
      of Environmental Impact Assessment Documents.                     ~    '

      U.S. Environmental Protection Agency.  1989.  Ecological Assessment of Hazardous Waste
      Sites: A Field and Laboratory Reference.  EPA/600/3-89/013.

      Wildlife Society, The.  1980.  Wildtife Management Techniques Manual. Fourth Edition:
      Revised.  Sanford D. Schemnitz (editor).  Washington, D.C.

In general, many of the same concepts described above (section 4.4.2) for aquatic life apply to
assessing impacts to terrestrial wildlife.  The assessor/reviewer must still determine the endpoints for
the assessment, including whether to consider impacts on individual species, populations,
communities, and/or entire ecosystems In determining which species or communities are of concern
in the affected area, there should be consultations with experts from State and Federal agencies.
Species' importance/value may be defined by legal (e.g., threatened and endangered listing),
commercial, recreational, ecological, or scientific value.  In some instances, it may be desirable to
                                             4-47                              September 1994

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             Enyironmental Issues
                                                                                  EIA Guidelines for Mining
             focus on certain species;  however, it is usually preferable, to assess impacts on the overall
             ecosystem.             	'  "           "          	'       '

             Biological diversity is often viewed as a way. to measure the health of an ecosystem.  For example, a
             decline f° fce species diversity of an area could indicate a deterioration in the quality, and possibly a
           	decrease in the stability, of that ecosystem.  Direct loss of mdiyiduals' (mortality) or a decrease in
             fecundity may affect species diversity. The above references describe available methodologies for
                             ..... ESSE:?.! ..... — ..... ,*S!!°n. ..... 2251 ...... *S3S ..... *€** imP301 is an important consideration for
                                ^,,!le, ...... E2!l!!!S!0,n P*1386 or during operations, for example, may displace .local
                                                         areas	surrounding the site.  Some individuals or
                                                           and
                           ,   .....         ,, ......     .....            .......    , .....      ......            ......          ,
•MjSHiS&ttpp^ operational activities. .Still other individuals may be permanently displaced for the life of
111111" lllllll!1 ill llll'llh 11 ' "111" 1111 "I1 IIHy lllil111111111111111111""11111111111111 llllli iiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiliiiiiiiiiiiii iiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiliiiiiiiiiiiii inn miiiiiiiiiniiiiiiiiiiiiniliiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiig game, and small mammal^ the objective of the
          program (qualitative versus quantitative); and numerous parameters such as the size of the project
                     !???             *                        c           ........ found ...... in ...... the project area.
                          methods that can be used to determine presence and relative abundance of wildlife.
                          jaaybe surveyed using Sheman live traps, pit traps, and snap traps. Raptors may be
                              " or on foot.  Auditory surveys are often used to survey for wildlife which is
                 t	to	observe	(e.g.,	songbirds	and	frogs). | Surveyors may_ count animals observed and/or rehr
       pSgjgSgj^ ^££1	IjackSj	scat,	etcj;	U£«U£gB	J£	PJ!!!E^	^PM	when	surveying for animals

                                                             
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EIA Guidelines for Mining _ Environmental Issues

The indirect impacts of a proposed action on wildlife near the project area should also be considered.
For example, a mining operation may be located to avoid impacting an elk migration corridor.
However, elk could be adversely affected by associated increases in housing construction which may
result from an unproved local economy.

NEPA documentation for proposed Dining activities should include mitigation measures which may or
will be used to minimize or avoid impacts to wildlife. Potential mitigation measures for use at mine
sites include:   .                                               .

     •  Avoid construction or new disturbance during critical life stages. For example, delay
         construction activities until after sage -grouse strutting occurs at nearby leks.

     •  Reduce the chance of cyanide poisoning of waterfowl and other wildlife, particularly in arid
         environments, by neutralizing cyanide in tailings ponds or by installing fences and netting to
         keep wildlife out of ponds.  Explosive devices, radios, and other scare tactics have
         generally not been proven effective.

     •  Minimize use of fences or other such obstacles in big game migration corridors.  If fences
         are necessary, use tunnels, gates, or ramps to allow passage of these animals.

     •  Utilize "raptor proof* techniques on power poles to prevent electrocution of raptors.  For
         example, use anti-perching devices to discourage birds from perching or nesting on poles,
         or place conductors far enough apart to ensure both wings don't contact them at the same
         time.
     •  To TTMT"T"i*e the number of animals killed on mine-related roadways, use buses to transport
         employees to and from the mine from an outer parking area.

     •  To limit impacts from habitat fragmentation, minimize the number of access roads and close
         and restore roads no longer hi use.

     •  Prohibit use of firearms on site to minimize poaching.

As noted above, mining operations can have substantial impacts on terrestrial wildlife, ranging from
temporary noise disturbances to destruction of food resources and breeding habitat. Unless closure
and reclamation return the land essentially to its pre-mining state, at least some impacts to some
individuals or species will be permanent. Coal mines, as discussed in chapter 6, must return the land
to its "approximate original contour" and revegetate as part of reclamation. When successful, this
can often minimize any long-term impacts.  Metal mining, on the other hand,  only rarely goes this far
                                             4.49                              September 1994

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                   iiiiiiiiii 1 iiiii iiiiiiiiiiiiiii iiiiiiiiii 111 ii illip     iiiiiiiii n n in iiiiiiiiiiiiiili ii i iiin i iiiiii iiiii iiiiiinnn i in in n innnn in i ill n iiiiin^^       ill iiiiiiiiiii i iiiiiiiiiiiliiiinii^^    iiiiiii iiiiiiiliii iiininn iiiiiiiiiii iiiiiiiiinniiiiiiiinn iiiinni i n  inniini iiiiiiiii in i i ill nil mi i in i in nil iiiinni|ii!ii!iniiilnilliiin iiiinnnnnni i nil iiiiiiiiliiiili|lii
                   IIIIIIH          Illlllll Illlllllllllllililllllllllllll II ••  I Illllllllllllllllilll llllllllll l llllllllll 1111 Illllll III II iiiiiiiiiii hill I nilini 11 I III I1 111 Illlllllllllllll llllllllll II IIIIIIIIIII Illilliiillllll III Illlllllllilll Illlllllllllllll I llllllllll llllllllll lllllllillll   111 I III 111 1 IIIIII nil llllllllll 11 III llllllllll Illllll Illlllllllllllll   llllllllll i IIIIIIIII Illlllllllllll
       I ill ill	in	ill	mmt	  ,  	imt	••	ii	ni	1111	
             Environmental Issues
                                  iiiill	Illllll	Hill	liililnl	Illillii	1 l»'|iii	Ill
	111III1	11	llllllfl	lliiilill             	Ill	lllllllilllilii|iilll	|i 111	iiiiiiiiiiiiiiiii
	BDV. Guidelines for Mining
iiliiiilH
                            although most disturbed areas are often returned to productive states following metal
    ill lli llllllllll
   lllllllllllllllllllllllllllllllllllll|lllllllllllllllllllllllllllllllllllllllli      lllllllllllllllllllllllllllllllllllllllllllllllll|lllllllll| |                      H                I      '                      	 v   	
   mhting. there are usually significant differences in topography and in vegetation.  These hi turn result
              a	jnjMcts	to	wildlife, in that they affect available fo^ water and coyer.	One of the major
               reclamation is to minimize permanent impacts, so reclamation plans are crucial to
   mitigation.  Because reclamation plans are often (or usually) only conceptual at the time of metal
   SHBC remitting,prejjarers and reviewers of EAs and EISs must often rely on applicable reclamation
   requirements aid on the processes that are in place to ensure that reclamation planning proceeds
	'	According to those requirements.       ••       .           '     	•	"	    •'•	
                     VEGETATION/WETLANDS
            Vegetation consists of natural and managed plant communities.  Native uplands consist of forests,
                     s and grasslands; managed uplands include agricultural lands, primarily croplands and   •
                       ................................................. li ...... ; ........ : ............ ! ................ I ............. ; .............. i, "              •       •                  ,  ~ .............. i ........................................ J_ [[[ =, , • [[[ • ......................................
                       ................................................. ...... ........ ............ ! ................ ............. .............. ,                       •                  ,   .............. ........................................ _
           pastures.  Lowland vegetation occurring within drainages forms riparian communities, including
                      21?- ...... il!iii§§!6! ..... feelow focuses on upland and lowland plant communities; the impact of
                   on agricultural lands is discussed below in the L?nd Use section
                !p. ..... giant ...... communities ....... Perform ..... a ..... number ...... of functions ..... in the ...... landscape. As discussed previously,
                  ion supports wildlife, with the diversity of vegetation strongly related to the diversity of
                                    Vegetation stabilizes the soil surface, holding soil in place and trapping
                                                        i ....... JE ..... SfeSSSHSS ..... IS ...... SS^

                                                                                  ..
                    soil moisture and lowering surface temperatures.  A diverse landscape also provides some
            tegipee of aesthetic value. | In the, case of rangeland, native communities, provide the  rimary
            ..... used ..... to ....... feed ..... livestock; ............... Riparian
                                                                      wetlands
           defined in Wetland Evaluation Technique (WET) Volume tt: Methodology (Adamus et al.,  1987);
                     ™®6* r?diaipj ........ @) ...... loodlPW ..... ftttenuation; (3) sediment stabilization; (4) sedunent/toxicant
                    ...... (5) ..... nutrient ...... ranpva|Aransfor|nati|M^ (6) primary production export; (7) wildlife diversity/
             mdance;	(8)	recreation;	and	(9)	uniqueness-and heritage."
              vegetetion within the active mining area is removed prior to and during mine development and
                                                             uaPacte^ ty m« roads, water diversions or other
          ,, ..............          .....            ......
          dixejpplient.  Vegetation further removrf from activities^ may be impacted by sediment carried by
    riMislsVi&iii	1°J|	and	by	fugitive dust.
                                                             	i1
                                                ..... Jojnegetation typically involves a study describing the major
      cainnninitjesi ....... or ...... associations, ...... withjn ..... ,the ..... affected area.  The description of each community should
      ,Jll ....... I ............... jil ........................................ S ............... II ............... I ............ lllllllillll ......... I ............ Illlllllllllllllll ........... I ............. II .............. I .................. | ................. I .............................. U ............. ; [[[ ; ............................. »»               I I   *  [[[ *

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  EIA Guidelines for Mining	.                	   Environmental Issues

  non-coal mines, the change in surface configuration may result in completely different plant
  communities being established.  Coal mines, under the SMCRA requirement to restore the
  approximate original contour and premining land use, often attempt to establish plant communities
  that resemble those tftat existed prior to mining.

  The requirements for defining and mitigating impacts to wetlands is more rigorous than other
  vegetation community types because of their protection under §404 of the Clean Water Act (see
  Section 6.1). The placement of dredged or fill materials into wetlands or other waters of the U.S.
  requires that a Section 404 permit be obtained from the U.S. Army Corps of Engineers (Corps).
  Permit applications must include a jurisdictional wetland delineation for each of the wetlands that may
  be impacted. Delineations are conducted as described in the  Corps of Engineers Wetlands Delineation
 Manual (USAGE,  1987), and are based on an assessment of vegetative, hydrologic and soils criteria.
  If "jurisdictional wetlands" are identified, the project must comply with the §404(b)(l) guidelines (40
 CFR Part 230).

 Compliance with the §404(bXl) guidelines requires mitigation for any impacts to jurisdictional
 wetlands.  The guidelines require mat avoidance of impacts be considered as a first mitigation option.
 If avoidance is not  possible, the guidelines further require the selection of an alternative that results hi
 the least amount of impact  to wetlands and that some measure of compensation be implemented for
 impacted areas. Under the guidelines, the Corps may not issue a permit if the discharge will
 substantially damage the aquatic ecosystem if practicable alternatives exist.

 Development of a mitigation plan should include an evaluation of the functions and values provided
 by the. wetland areas under analysis, the extent of proposed disturbance (acreage), and an assessment.
 of potential cumulative impacts to surrounding wetlands.  Based on these site-specific factors,
 mitigation requirements are usually established on a case-by-case basis. Mitigation may involve
 restoration, creation, enhancement, exchange, or in some cases, preservation of wetlands located
 either onsite or offsite.

 The assessment of wetland functions and values, in the context of a mitigation plan, tend to be
 inherently subjective.  While functions are tied to properties of the wetland itself, value tends to
 reflect societal influence and are necessarily subjective. However, the proximity of one wetland to
 others, the uniqueness of a particular wetland, .and  the number of functions it performs all influence a
 wetlands value.  Mitigation considerations include whether the target is to be an "in-kind"  or  "out-of-
 kind" wetland in terms of functions or community types compared to the original.  Location (onsite
 or offsite), timing (before, concurrent, or after), and mitigation type (restoration, creation,
 enhancement, exchange, or  preservation) are other variables that must be considered in developing a
mitigation plan.  Depending on the variables involved, the ratiaof the areal extent of compensation to
disturbance can range from  1:1 to more than 3:1.  Barring avoidance, the preferred approach would
                                            4-51                              September 1994

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                                          liii'ili
        Environmental	Issues	
                                                                                  EIA Guidelines for Mining
[[[ .................... began.     uci a
                                             in-ldid and onsite, completol before development activities
                                                              "
                                   stor:iinpacted ratio may be cose to 1:1. The ratios increase in
             situatipns ,
                        succss can only be acjrieyed through a greater degree of difficul^ or when the

:        mitigation cannot be completed before initiation of the project (Kruczynski, 1990).
        Wetland restoration and creation tends to be as much art as science under the current state of
        knowledge.  Therefore, success should be evaluated using a set of clearly defined goals to be achieved
        within a specific time frame.  Goals should be established in the planning stages. A monitoring plan
        should be developed and implemented to ensure that newly restored/created wetlands progress toward
       ........ the previously ..... defined target ...... in a ..... timely ...... manner. .............. The ...... establishment of clear goals and an effective
        monitoring plan are of key importance to project success but are often overlooked hi the planning
       i iiiiiiiiiiiiiiiiii iMiinnnnnnnnnininninninn 1 1 nun «iii««iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii|||iii nuiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiifim ........................... iiiiiiininn ...... nnnnnnnn ...... niiiiiiiiiini ..... iLiin ........... ..... i .......... in [[[ i ...................... n     i j nn   i ik in ...........    i   n i  \  r   ........................... S ...........................................
       stages.
                                                           nh ii ill i I 111 II |l IIIII lull i II ill II 111 11 III i
       4.4.5    LAND USE
           i            n                     •                 •
       Metal mining nearly always results hi significant changes to beneficial uses of land after mining.  A
       description of land use should identify the current use of land needed specifically for the mine and
       land use patterns in the nearby area that will be indirectly affected by the project.  Particular emphasis
       should be placed on land uses that pose potential conflicts with.mining operations—farming timber,
       grazing, recreation—and on the local or regional zoning laws that may limit the development of
       m|n|Tig	operations.
                  Farmland
           U.S,	Soil	Conserv^on SwjS.SS!,,-	S2Fged *"***
                                                                             and	locating	Prime and	Unique
           fermland under Public Law 95-87.  The SCS works with State and local agencies, to identify
           fiuTmand of statewide or local importance.  Farmlands in the vicinity of the mining project under
           evaluation should be identified by SCS categories.

           iSiiilS.!^13^ maintains lists -of all soil series that fall into the categories of grime, unique, and
           State/locally important. Depending on location, lists may be generated and maintained on a county,
                          	llill	(1	Ill	I	|	ill	Ill	lIllH	HI!	 J    °   1         	  	iZmmm	SiiiXS..!	
                 _^_               	"                    ~    ~   <         	'	'	•	   " '	
              21,	?tatewide basis.  Where appropriate, the reviewer (or the applicant) should contact SCS (or
                    State/local agencies) to verify the existence of designated ^^^ ^ ^ vicmity Of a
      proposed mining action.
                                            best combination of physical and chemical characteristics for
     producing	food,	feed,	forage,	fiber,	and	oilseed	crops that is available for those uses. Prime farmland
                                                 i and exists within
               characteristics mclude a lack of rock fragments, a pH range of 4.5 to 8.4, water holding
      capacity to a
      i'illlllllU! IIIIIH^^^^
                             of 40 inches and adequate to produce
, and an average annual soil

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 ~E3A Guidelines for Mining                                               'Environmental Issues

 temperature of greater that 32°F at a depth of 20 inches.  The prime designation also relates to the
 availability of irrigation or a sufficient precipitation regime to sustain crop production.

 Unique farmland demonstrates similar characteristics to prime soils and produce high value food or
 fiber crops. However, these soils lack a particular characteristic that separates them from prime -
 precipitation for example, may limit crop production to eight out of ten years. Soils of statewide or
 local importance are identified based on unique characteristics identified on a local basis.  Local
 conditions or characteristics restrict, production on these soils to a greater extent than soils classified
 as prime and unique.

 In addition to prime, unique, and State/locally important farmland, EPA's September 1987 policy
 identifies three other types of environmentally significant agricultural lands  for protection.  These
 include:  farmlands in or contiguous to environmentally sensitive areas, farmlands important for waste
 utilization, and farmlands with significant capital investments in best management practices. Such
 determinations are made on a site-by-site basis.

 Potential impacts from proposed mining  actions to farmlands can range from complete elimination of
 the land for fanning use to temporal cessation in farmland production.  Analysis under NEPA should
 specifically consider the effects of an activity on the important soil/farmland categories described
 above (as well as the feasibility and likely effectiveness of proposed mitigation measures). Wherever
 possible, mitigation measures should allow for returning the land to its previous productivity.  For
 example, the operator could strip a particular soil series by horizon and stockpile each separately,
 with die intent of restoring the soil profile upon completion of mining.  Under SMCRA, coal mines
 are required to restore prune farmland to its previous state (no such uniform requirements exists for
 noncoal mines).

4.4.5.2    Timber                                   .

Timber lands should be identified in the project area and the board feet of lumber represented by that
timber should be estimated.  Impacts .to timber are typically the loss of the resource in the. areas to be
 cleared for the mine.  Mitigation of the loss of timber lands includes the economic harvest of the
 existing timber prior to clearing and construction of the mine.  Reclamation of the mined areas may
 require the replanting of trees but the land may be rendered unusable for timber growth at the close
of mining as a result of poor growing media, or the presence of large excavations. Any mitigation
measure that calls for tree planting (or, indeed, any revegetation) should include monitoring for
 several years to verify its success.
                                             4-53                             September 1994

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 11 iiiiiii 111 iiiiiii iiiiiiiini i in i nil i in n 11 |iiiiiiiiiinninnn nn in iiiiini in in i in 11 in iiiiiiiiiiiiiiiiii n111 innninnUi iiii iii iiiinni in in i iiii "i n n n in i nn iiiiini in iiiinni n i nn 11 in n iiii'in in 1111 M nn iiiii nn iii n in i n i n iiii i nn MM nn in 111 in iiiiini nn 11 n i in iii i iiiiiinii mini iiiinni iii iiiinni inn i iiiinni 11 in' i in in iiniiii n n i in n in iiiiini I in iiii 11111 in 11 inn n in n nn iii i n i in i  n inn nn  in in ninii|niiiinnn iii i nn i iiiiiinn|n i n' iiiiiinii n 111 i in i in iiiinni
 i| 'I'lllllllllllllllllllillillllllllllllllllllll I'M..!!..          .  n IIIIIII Illllll  mmw 111 i IIP III Illllll fill lliilllllllllllllllllPlllllllIIII  i 11 IIII1! V 'III	lillil«i««l««|i II III 1 Iiiiiinii 111 •lillnlllPllli'll MM1 \ III III ill	11III ill Illllll II«|I Illliillllllllillilli^       'IliliIIIIIilllll   	IIIII 11 IIIIIIIIIIIIIIIIII III 1111^     I 111 III Illllll
 iiiinni iiii iii iii i n iiiiiii  iiiiiiiini nn n n iiiiini nn iiiinni 11 in in iii i  iiiiiiiiiiiiiiiiii i in n iiii in p i in ii i ni nil iiii i HI i in i n iii 11 iiii n  iiinnin inn n  iniiinini i n i  nil in n inn  nn iiiiini i in iiiiini  iniiiniiiiniii|iiiiiniiiiiiiiiiniiiiiniii||iiiiiiinii iiiiiii in i inn n n i linn nn i iiiii i	
 jn p in in M ii HI g i	in, iii iiiii 11,1 iiiiiiiiiiiii iiiiii ii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii in iiiiiiiiiiiiiiiiiiiiiiiiijii n i iiiiiiiiiiiiiiiiii nn 11 nil n 11 iiiiiii niii iiiiiii iiiiiii Ii I in1"	'	   iL	'"  		"	
 ill   i'  v i piniiiiiiiiiiiiiiiiiii in 1111111 iiiiniiiiiiiiiiiiiiiiiiiiiiii iiiiini ill i 1111 iiiiiiiiiiiiiiiiiiiiiiiii i iiiiii nn nn ni nn i nn ii1ill inn I'liii in i in inn nn 111
 	!	'	  Environmental Issues
                                         n  iiinnin inn  n  in n nn in i in i n i  nil in n iii  nn iii i in  nn  in in in |i i ii iii inn iiiinni i iiiiiiiiiiiii •• in i inn n n iiiii i iiiii in in in iiniiininii i  i   HI  nn 11 iiiii in  iiiii  iiiiii
                                           inn •  if«ii'i iiiiii iiiiii iiiiiii   i1 nii in	mill iiiiii Tiiiiiiiiii	iiiiiiiiiiiiniiii    1 iiiiiiiiiiiii iiiiiiiiiiiiiiiiii   	iiiii iii iiii iiiiiiiiiiiiiiii       '»iiiiiiiiifiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiii
ii iiiiii iiliiiiiiniiiniiiini

 4.4.53
                                                                                EIA Guidelines for Mining
                        Grazing
           The extent of lands used for grazing should be identified within die vegetation survey conducted for
           the site.  The area! extent of each plant community in which grazing occurs and the extent of
           disturbance within those communities should be reported. The animal unit months (AUMs) each
           coinmimiry is able to support and vegetation biomass data should be included.  Where slopes of pits,
           benches and highwalls do not prohibit it, reclamation in most cases will readfly support grazing in the
           post-mining landscape.
          4.4.5.4     Recreation
                 m the area of proposed mining projects may be used for public recreation.  The types of
          recreation provided by the lands in the vicinity of the project should be identified!  Potential impacts
          should be described with respect to the current level of recreational use as well as opportunities for
          additional uses. The extent to which recreational uses will be restored after reclamation should also be
         '4.4.6     CULTURAL RESOURCES
                                                 iiiii ,( ' i1 ...... iiiii H ...... ' ....... mum iiiiTiinii IH ii ...... 1 1 1 ii •iiiiiiiniB     "    i ...... .......... wmmtf ..... I'liiii 1 11 ........ IM ....... i in in ....... iiiii < " ii  ' i no ii'i
        i ....... Cultural resources ...... encompass several areas relating to man's knowledge and appreciation of
         prehistoric and historic events.  The location of a mine or beneficiation faculty at or near significant
                                                                                                                    •iiiii
                                             felSSllg ..... J?nds ...... of sites ...... should ...... be,,,,,described ..... .irrrelation ..... to .the project
                                                                          •       	mmm
                                                                                                                                 •
               f.    Arjcheological sites (where man-made artifacts or other remains dating from prehistoric
                    times are found).  These are not uncommon, particularly in the west.
               *:=:l^epi^lpgical sites (where significant events happened or where well-known people lived
                       worked).  Again, these freouentiv occur on proposed sites in the west.
                                              ional, religious, scientific, or cultural value.  Once again, these are
                               encountered, particularly .in the west. Native American values (including
     5r3!m'iCin£!£2ii!0*B	and	cultural	values	associate^	with	certain areas) are of particular concern.  As
                   opted in Chapters, artifacts and remnants of historic mining are also increasingly being
                   protected	asiultujal	resources.	]	
z^=£:	™.,i^™! I;*	;	;,	BEPpcrttes on or eligible for listing on the
                   106 of the National Historic Preservation Act.
        i	""iiv'iniii: ih iiiiiiiiii«iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiihiiiiiiiiiiiiiiiiiiiiiiii«iiiiiiiii«iE^      111111111111111 .u, iiiiiiiniiiiniiiiiniiiiinniniinii     i	11 iiiii; 114111111111111111111 iinniiiiiiini 11 ii'n i in in iiiiiiiiiiwiii ini n iiii inlii iiiiiiiiniiiniiiiiiiiiniiiiiiii iinnnii i in in iiiiii 111 n in win IIIIIH
                                                                Register for protection under Section

                                                                             I IIIIIIIIIIIIIIII HI I IIIIII 1111! 1 lull 11 il 1111III ' 11111 ll|li i IIIIIIIIIIIIIIIIII 111  i 111 nl nl III

                                                                             ,  a discussion of mitigation
                                                                                                                             I HI IIII lull II il i I'll "I I ill III
                            iiinnnnl  n ill iinnnili n nniii n n n ill nn i n 11 inn ii in nn n in iiiiini

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  EIA Guidelines for Mining  	   •  '	Environmental Issues

  4.4:7   AESTHETICS

  Aesthetics involve the general visual, aural, and .tactile environment.  A description of the aesthetic
  characteristic of the existing environment should include things that are seen, heard and smelled hi
  and around the site and their emotional or psychological effect on people. Descriptions (or pictures)
  of views of the site, of unique features or features deemed of special value, and public use and
  appreciation of the site provide information that must be available for the assessment of impacts.

  Potential aesthetic impacts include the loss of visually pleasing areas as ground is disturbed and
 previous surface expressions are eliminated or damaged.  Mines typically create significant noise
 above the baseline conditions (from blasting, heavy equipment operation, materials/waste transport
 and disposal, etc.).  Mitigation measures to address aesthetic impacts involve siting of mine features,
 as well as facility design and mining practices.

 4.5    SEDIMENTATION/EROSION

 Because of the large area of land that is disturbed by mining operations and the large quantities of
 earthen materials exposed at sites, erosion is frequently of primary concern at coal and hardrock
 mining sites.  Erosion control must be considered from the beginning of operations through
 completion of reclamation.  Erosion may cause significant loadings of sediments (and any entrained
 chemical pollutants) to nearby streams, especially during severe storm events, as well as high
 snowmelt periods.

 Major sources of erosion/sediment loadings at mining sites can include:

      •   Open pit areas
      •   Heap and dump leaches
      •   Waste rock and overburden piles
      •   Tailings piles
      •   Haul roads and access roads
      •   Ore stockpiles                                             .
      •   Vehicle and equipment maintenance areas
      •   Exploration areas
      •   Reclamation areas.

The variability hi natural site conditions (e.g., geology, vegetation, topography, climate, and
proximity to and characteristics  of surface waters) combined with significant differences in the
quantities and characteristics of exposed materials at mines preclude any generalization of the
quantities and characteristics of  sediment loadings.  Further, new sources are frequently located in
areas with other active operations as well as historic mines (left in an unreclaimed state). There may
                                             4-55                              September 1994

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             Environmental Issues       	   	        EIA Guidelines for Mining
            also be many other non-mining sources of erosions in the watershed (other types of industrial
            operations, naturally unstable areas, soil conditions, etc.).  Therefore, in considering the erosion
            effects ftom a new mining source, the cumulative impacts of sediment loadings from all sources
    •       	within a watershed need to be considered. An important element of this analysis is the potential for •
            the new source to alter downstream .flow conditions and thereby alter rontribjitions from downstream
            sediment sources.                            .               .
           ifThe foggwjng subsections describe: (l)'the basic principles of erosion, (2) the impacts associated
            with ...... erosion/runoff (i.e., the physical/chemical effects on the watershed), (3) approaches to
                       ^ basdine conditions, (4) methodologies to determine the sedunent <»ntnbjtigns,frj>m a
           .^                  ,
::=^^
            and ^treatment feghnnlfigies).
           4.5.1"  BASIC J&OSION PRINCIPLES
            Water erosion ...may be described as the process by which soil particles are detached, suspended, and
                                ..... source ...... of origin. Sedimentation may be described as the by-product of
                                                        -

                   whereby eroded pgies gj-g deposted   a jratt  ocation than mg S0urce of origin. Soil
                   [[[ ,1- ...................................... I, ......................... ± [[[ i ........................... i ........................ s [[[ ; ........................................... i ...... ; [[[ i ........ , ....................... . .......... i .................................................. .,- ............................... . .......... .............................. o
          [oetadnnent ..... results ...... from ...... thejsneigy ...... tfnundrops striking the soil surface or it  results from suspension
                                                                                            Erosion ................ " ..... ..... ........... '"
           occup from the movement of water in sheet flow, in rills or gullies of ephemeral waterways, or
           through channel erosion in ditches and streams. Wind erosion occurs when wind energy exceeds the
           SfMlttV /\T O/\ll tf\ f*TTlf»?-n /*/\VkAC***r^ «i«t«] +)«A ««M«*«MlAn 1& «««.**. A. J«*AA^._^>  T-_i-._1I __  __ ! __ i ____ •__ •_ _
       ™t*fcJIiS	(Qfsott	to	remain cohesive aad	the particles become detached.  Typically, wind erosion is a
         .  problem in arid climates.
               i
                     > influencing	erosion	and	sedimentation are interrelated	and	all relate to either the impact of
                       or runoff velocity and volume.  Sedimentation is considered the final stage in the erosion
           process, thus the mechanisms affecting erosion also affect sedimentation. .The main factors
           influencing erosion include:
                *
               i
                    Rainfali/Snowrndt ganoff,, The volume and velocity of runoff from storm events are
                    dctennined by the	rainfall	intensity	and	the duration i of .the	rainfall	event.	A	more	intense	
                    stonnlpplies greater forces which results hi greater displacement of soils; storms of longer
                    duration naturally produce more runoff, and thus greater erosion. Runoff also occurs
	*u?1?	22222S!!,	E®55ds_	(552*	Y.5I5I15	.?Sd.y
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EIA Guidelines for Mining	              Environmental Issues


     •   Soil Texture and Structure. Soil texture describes the percentage composition sand, silt,
         and clay particles in a soil.  Soil structure generally refers to the aggregation of soil
         particles.  Sand particles are heavier, and disregarding aggregation are generally less
         susceptible to transport than are. silt particles. Soils with high clay content are also less
         susceptible to erosion because the particles tend to stick together. Soils high in silt content,
         on the other hand, unless well aggregated, are the most erodible soils.  The structure will
         influence the erodability of each type of soil. Well aggregated soils are less likely to,
         detach. Runoff or airflow over these soils however may be increased, due to
         impermeability and-thus reduced infiltration. The relationships between soils type and
         structure and potential water erosion are well known, yet complex.  (Similar principles
         apply to water erosion of waste/materials management units.)

     •   Vegetative Cover.  Vegetative coyer influences erosion by:

            Reducing the rainfall or wind energy striking the soil's surface
            Lowering the velocity of overland and channel flow which:

            —  ' Reduces peak runoff rates and resultant impacts of channel erosion, and
            —    Decreases the velocity of overland flow, enabling sediment deposition to occur
                  closer to the original site
            —    Providing  roots to hold the soil in place.

         Because vegetation acts in multiple facets, the relationship between vegetation and erosion is
         dramatic.. This is perhaps best illustrated through curve numbers. Curve numbers are used
         in the U.S. Geological Survey soil-cover complex method for estimating rainfall runoff and
         are an estimate of the percentage of rainfall runoff that will occur.  The curve numbers for
         forested land of varying soil conditions range from 25 to 83, meaning that forested lands
         will produce from 25 to 83 percent runoff.. In comparison, the curve numbers for a
         denuded construction site of varying soil conditions, range from 77 to 94.

     •    Slope length. The term "slope length"  is defined as the distance from the point of origin
         of overland flow to the defined point of interest, which may be a channel, or the point
         where deposition begins. Longer sloped surfaces result hi higher runoff velocities for the
         particular segment.                          '

     •    Erosion Control Practices in Place.  Various practices and structures can be employed to
         reduce the effects of land disturbances and developments: Erosion control practices work
         by one or more of the following mechanisms:                                       •   ,

            Reducing the impact of raindrops
            Reducing the runoff volume and velocity
            Increasing the soils resistance to erosion.

         Specific erosion control BMPs applicable to mining sites, are described in Section 4.5.5
         below-
                                             4.57                              September 1994

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gi i g in 111 in i Hi nil inn i I mm iiiiini nil iiiinin iiiiiiiiiiiiiiiiiiiiiiiiiinni iiiiiiiniiiiiii iiniiiiiinniinn mi i inniiinin in i iiii i iiini i miiiii m i fin i f' iiliiiniinnn iiiwi n i inn inn	nun vn nniin ininn niiiinn i in in n n inn i inn n 111 in 111  i n 11 in ninn in  i n i n n nn 11 in i in IIIIHIHII 11 nn in iiiini i n i iinvm in iiniinniiiiiii PIIII inn nn nm i niiniiiini n nniinniiinniinniliiiinninn »i iiiiiiinniiiiiiiiiiiiiii i i i«iiiiiin i inn inn 1111111111 in n n PII i in nn n i inn n in 11 nn i« in
        jnilrnnmental Issues	          EIA Guidelines for Mining
        4.5.2    IMPACTS ASSOCIATED WTIH EROSION/RUNOFF FROM DISTURBED AREAS
        Paniculate matter is toxic to fish.  Decreased densities of jnacroinver|ebia|e and benthic invertebrate
        populations have been associated with increased suspended solids.  Enhanced sedimentation within
        aquatic environments also has the effect of inhibiting spawning and the development offish eggs and
        larvae, as well as smothering benthic fauna. In addition, high turbidity may impair the passage of
        light, which is necessary for photosynthetic activity of aquatic plants.
                        i               ,
            "            .      HI I Illlllllllllllllllllllll II II HI I 111 Illlllllllllllllll Illllll      I Illlllll III PIIII 111111 111 III 111 111 111 I III UIHl 111  III I II  IIII II Illllll 1111  III IIII  I 111 I 111 1 1 11  III II
        Further, exposed materials from mining operations (mine workings, wastes, contaminated soils, etc.)
        may contribute sediments with chemical pollutants, including heavy metals.  Contaminated sediments
        in surface water may pose risks to human health and the ..... environment ...... as ...... ^ persistent source of
                ...... Bi ......      ..... SSl ..... m^3^ Iife' ,Human exposure occurs through direct contact, eating fish/
                                                                 w            ° contaminated
                                                                   ,        ,,,
       sediments. Continued bioaccumulation of toxic pollutants hi aquatic species may limit their use for
       human consumption. Accumulation in aquatic organisms, particularly benthic specifies, can also
       causej acute and chronic toxicjty to aquatic life.  Finally, organic-laden solids have the effect of
       reducing dissolved oxygen ..... concentration, ....... thus ..... creating toxic conditions.. There areno National,,
       sediment criteria for the toxic pollutants likely to be released from mining sites, although criteria for
       metals are currently under development and some States have established sediment standards.
                                     ..... impacts ...... on ..... human ...... and ..... aquatic life, mere are physical in^iacts
                lil ...... gfeJRSJJassd ...... SSnpivejocities ..... and ..... volumes from new land disturbance activities.
               SliiSii ...... ml ..... Hiiiili .......      ..... JBSaaasa& ..... flooding, scouring of stream channels, and
      itfilc tural damage to bridge footings and culvert entries.
      A characterization ...... of background conditions within a stream .is necessary 'to assess the potential
              == ...... ^^^^^^^m^^^ ................ A£ ..... iSPO!!??! ....... element in assessing baselme stream
                               S5 ...... S^-felS?!^,!31?!!!*^ 2f ^ ,S!F,eam- 1E4, (1989b) has suggested
                               stream parameters be characterized at each stream sampling station in the
                                    "
                            SUSHIS tond use- A description of the predominant types of land use is
                                            land uses may also potentially affect water quality.
                                            PB                     	                    '          l!'iKB18fi!'SMiil'!l!f!H
                               SaaSSs	4	ZHSl	estimate	of erosion can be made by observing the'
                             SEfSSS SPii the, stream characteristics (both channel characteristics and
               sediment loads). •
           •   Estimated stream width.  A representative transect should be measured from shore to
               shore to provide an estimate of stream width.
                                                  4-58                              September 1994

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 EIA Guidelines for Mining                                               Environmental Issues

      •   Estimated stream depth. Stream depth should be determined for three habitat types: riffle,
          run and pool. Measure.the vertical distance from the water surface to stream bottom.

      •   High water mark. Measure the vertical distance from the bank to the peak overflow level.
          The peak overflow level may be indicated Toy debris hanging in bank or fioodplain
          vegetation or deposition of silt or clay.

      •   Velocity. Stream velocity should be estimated in a representative stretch of the stream.

      •   Dam/obstacles to flow present. The presence of a dam upstream or downstream of the
          stream segment under study should be noted.  Also, any other impediments to flow or
          sediment transport should be noted.  How the dam or obstacles affect flow should be noted.

      •   Channelization. Describe whether the .stream is channelized at any point along the stretch
          of stream under study.

      •   Canopy cover. A description of the percentage of shaded area at each sampling station
          along me stream should be provided.

      •   Sediment odors.  Any odors emanating from the disturbed sediment should be noted.

      • '  Sediment oils.  A visual estimate of the proportion of any oils in the sediment should be
          noted.                     .

      ••   Sediment deposits. A description of the type of deposits present in the stream (sand,
          sludge,  organic material,  etc) and any blackened undersides of rocks (indicates low
        '  dissolved oxygen or anaerobic conditions).

      *   Inorganic substrate components. A visual estimation should be made of the percentage of
          inorganic substrate components present.

      •   Organic substrate components. A visual estimation should be made of the percentage of
          organic substrate components present.

This method for evaluating the physical condition of a stream can be made more rigorous by
including  quantitative evaluations of sediment transport.  A quantitative evaluation of sediment
transport may be more suited for areas where significant disturbances already exist and more rigorous
documentation and understanding of the baseline conditions is necessary. Quantitative measurements
may be made of suspended and bedload sediment in the stream, as well as measurements of sediment
deposits (sediment .bars, substrate, etc.) and turbidity (turbidity measures the ability of a fluid to
transmit light).  These data provide a rough estimate of the concentration of suspended sediments hi
water. A quantitative baseline measurement may also be made of the stream channel throughout the
area of impact.

The sampling of suspended sediment can provide information on the physical and chemical
characteristics of the sediment hi suspension. Depth-integrated sampling, as opposed to point
                                             4.59                             September 1994

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                                                                                                         	ll
         Environmental Issues
EIA Guidelines for Mining
           if .        "  ,'ii !"   ""''i        •   ' .   ""         ,'          •     ..       i        I '        •   ,
        sediment and adsorbed constituents (USGS, 1977). Depth-integrated sampling involves the use of a
        depth-integrated sampler that is lowered/raised throughout the depth of the stream at a constant speed.
           'I ''" '     ''  "'  T"||l!l!|"      '         '                            ' i           	              r
        If the depth-integrated sampler is also used to sample across a stream transect, the concentration of
           I) ii
        suspended sediment obtained can be multiplied by the water discharge through the sample zone and a
           \               i   A (   i    i           ; .            i        ,       .1    v
        total suspended sediment discharge can be obtained (USGS, 1977). Consequently, to provide an
        accurate measurement of suspended sediment loads hi a stream, samples  should be collected near
        stream gauging stations.
        Sample site selection should take into account the following preferences: located near a stream
           |i          i          i               i     i        » '             '       ~ i i
        gauging station, located away from any flow distorting obstacles, and far enough either upstream or
        downstream of confluences to prevent the hydraulic variances that exist in those zones (USGS, 1977).
        Frequency of sampling should be determined by the known historical streamflow or precipitation
        records, at a minimum, the stream should be sampled at periods of annual low and high flow.
           I             i  "             I                   In
         •                 Illllll 11 1111 111 111 ill 111 111   111 11 111 ll III II 111 IIIIIIII 111 I III II 111 III  I  I 111 I II III 111 I 111  Illlllllllllllllllllllllllllllllllll III III Illllllllllll  III III Illllll 111 lllllll 'I   II I HIM ll 111 I I III  1   111 I I
           II          i                                               i          r    |          i
        Sampling of the deposited sediment in the streambed can provide a wide range of information
        including the type of sediment available for transport, mineralogy of the sediments, stratigraphy, and
        amounts and distribution of contaminants (USGS, 1977).  Sampling methods are available for
        collecting disturbed or undisturbed samples.  For the purposes of baseline sampling for a mining
       project, an undisturbed sample may not be necessary.      .
       In	addition	to	a physical characterization of the stream, a habitat assessment should be conducted to
       determine the baseline conditions of the stream's ability to support aquatic life.  The parameters to be
	assessed represent measurements/observations of substrate	and instream	raver, channel morphology
       and riparian and bank structure.  EPA (1989b) has identified the following parameters for evaluating
       the baseline conditions of stream habitat.                       .
                Bottom substrate/available cover.  A visual observation of the ability of the bottom
                substrate to provide niches for aquatic life should be madeT
                Embeddedness. Embeddedness refers to the percentage of fines surrounding large size
                (boulders, rubble or gravel) particles.

               	Stream Jlpj?/sjream	ydoqfty. The volume and velocity of stream flow should be evaluated
                     resj>ect to optimal conditions for aquatic life.
                i Chaindl	alteration.	An	observation	of growth or establishment of sediment bars or other
                 ___  —         changes hi upstream erosion. The development of channelization
               	.ihojjld	ilso,	benoted,.
                                                                                      September 1994

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 EIA Guidelines for Mining                                               Environmental Issues


      •   Bottom scouring and deposition. An observation should foe made of the degree to which
          the substrate is scoured and the amount of siltation in riffles and pools.  This observation is
          typically reported as a percentage of the observed stretch that is scoured or silted.  Bottom
          scouring and deposition result from sediment transport and may provide an indication of
          watershed erosion.

      •   Pool/riffle or run/bend ratio.  This ratio is calculated by dividing the average distance
          between riffles or bends by the average stream width.  This parameter assumes that the
          higher proportion of riffles and bends provides more diverse habitat than a straight or
          uniform depth stream.

      •   Bank stability. Bank stability is typically determined by the steepness of the bank and any
          observed erosion into the stream. Steeper banks generally indicate poor quality instream
          habitat due to mere susceptibility to erosion, however, stream banks of clay may not be as
          susceptible to erosion as stream banks composed of other sediment.

      •   Bank vegetative/rock stability.  Bank stability may also be estimated by the type and
          amount of vegetation and rock cover present. Proportions of shrub, trees, grasses and
          rocks providing bank cover should be estimated.

      •   Streamside cover. An estimate of the primary type of vegetation that is providing
        •  streamside cover should be made  It should also be noted if no cover is provided.


The above information on the sediment and habitat quality should be considered in conjunction with
baseline studies of aquatic organisms within the watershed (including fish count, macroinvertebrates,
etc.). The combined data will allow the reviewer to correlate background aquatic life conditions to
sediment quality.


4.5.4   PREDICTING SEDIMENT LOADINGS FROM NEW SOURCES

There are  currently several approaches/models available to assist in the prediction of sediment losses
and flow responses of basins both before and after landscape alterations due to mining and other
human activities. As with any models, they are highly sensitive to the input data supplied and caution
must be used in identifying and quantifying the important factors for a specific project.

The primary factors affecting basin sediment yields are:


     •   Precipitation. Volume, intensity, and duration are all important

     •   Vegetation.  Vegetation increases the ability of hillslopes to retain overland flow, increase
         infiltration, and reduce the velocity of overland flow

     •   Basin size. Basin size controls the lagtime between the beginning of the storm event and
         the time of peak flow
                                            4-61                              September 1994

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             Environmental Issues
                                                                         El A dlirlelinpc fnr IVTini
                                                              ijjjBT,,,., •'!,,,- 1 « i ' it ;:: ' ....... »
                                                                            ! 'iilE 'i !! « ' Li, " ....... Hr , ........ i :«]!!!:", iii,i - 'I!!!1!11:,, i, ift,1! ..... ¥ ' '
                 aS	i	!	I|lli||fil	iil	ffiliik	IUPS	With	steeper overall slopes will have higher overland flow
                     "~x?cities and quicker response times to storm events
                     SoM/rock type. Different soil types have varying degrees of erodability, infiltration
=^g>=g2=»~i»;,;jdellng basin hydrology can take forms varying in complexity from "back of the envelope"
     calculations to cojnputer-based, multivariate modeling based on data from comprehensive field
     investigations. Most modeling, of any level of complexity, is based on several basic equations
     developed specifically to predict soil losses from known bashi characteristics.  These equations
     include: the Universal Soil Loss Equation (USLE), the Modified USLJE'"(MUSLE), and the Revised
     USLE (RUSLE). These equations are	dcsaSbedbdaw.	:	\	'.	'	

     The Universal Soil Loss Equation (USLE)
	I	"	                        i	!	 "	    '      •    i "
     The USLE has been developed utilizing data gathered at a large number of experimental sites. The
     equation utilizes six hydrologic variables  to |enerate predictions of .annual total soil loss in tons per
	i*^^	£S2	ifSSlS	ISlS;	SHS	2l, IE	SSE^P-B.	^F^68 are determined lay comparing site'
        5c observations, of bashi characteristics to published graphs and tables to determine the
                                                                     of the
                     ...... yfto£. ............. The ..... U.S. ........ Soil ...... ComgrattaSovite ..... pribUdies
           SIS? ....... 2!S£S ..... ,l2Xg,i,ISffl4Sy£!PI^ .fr0111 numerous studies of bashi characteristics: ..... ma number ...... of
           climates.
          The tTSLE is written:
   iiiiiini
    Where A is the total soil loss in tons per acre per year, R is the rainfall erosivity index, K is the soil
    erodabflity index, LS is the length-slope steepness factor, C is the cropping management factor, and P
    is the erosion control practice factor. An increase of any of these factors will result hi increases hi
    the total predicted soil losses for an area.

    The Modified Universal Soil	Loss	Equation (MUSLE)
                    I    '                                              i i      I    i
   The MUSLE equation is written hi final form identically to the USLE.  It varies from its predecessor
   in the introduction pf an exponential function for the deterrnination of the length-slope factor (LS).
   The T^—	t?I^2°-	5?!	,!^n.	**E!EL	!°, ,'w,?,!l	™*	PS,	51PP??	HP	to	15	to	20 percent but on steeper
   slopes prediclions of erosion become much greater than those  actually observed. The R-factor is also
         '                                         ,11 .in   ,„     n
 i••• i^     	iiiii	ITmiitu	iiiiiiiirinMUM ifiiiiii < 11I1111 'iiiiiiiiiiiii	" uiiiiiiiiiipiiiiiiiiiiiiiiiiii1 iiiiiiiiiii,, i	•	' TK	
 	1	4-62
                                                            	September 1994

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 EIA Guidelines for Mining	Environmental Issues

 changed and,is now a product of the total per-acre runoff volume and the maximum rainfall intensity
 for a given storm.

 MUSLE also improved its predecessor by allowing predictions of soil losses for single storm events.
 This is important because allows for the examination of losses during peak conditions which may
 account for a large percentage of total annual losses.

 The Revised Universal.Soil Loss Equation (RUSLE)

 RUSLE takes the same basic form as both the USLE and MUSLE.  However, the RUSLE improves
 upon both previous incarnations by using several LS functions to model slopes of different steepness.
 Of the three approaches, RUSLE works best for steep basins (slopes greater than 20 percent).

 Other Son Loss Equations

 Several other soil loss prediction models have been developed that are based less  on standardized
 tables of factors and equations but are instead theoretically based. These models  are, important in that
 they allow for the testing of hypotheses on the physics of hillslope hydrology. However, to date, they
have not yet been shown to be accurate predictors of total sediment losses and so remain more
theoretical than practical.             '"..-..

Computer Models

A number of computer models are available which utilize variations of the USLE and other soil loss
equations to perform automated analysis of  soil losses from basins.  These models are available from
commercial, governmental, and academic sources.  The most sophisticated of these allow for the
subdividing of larger basins into smaller sub-basins and utilize routing functions to predict the
response to the same storm of sub-basin areas which may have very different soil, vegetative and
land-use conditions.

4.5.4.2     Modeling Considerations

In. the use of any of the above modeling schemes, the accurate determination of current and potential
 site conditions is vital to generating, accurate results. In some  cases, what seem to be fairly small
variations in site conditions can make great differences hi predicted soil losses. For example, the
 cropping management factor, C, can vary by a factor of 3 with a change hi vegetative cover of 20
 percent (U.S. Soil Conservation Service,  1975).  Under- or over-estimating canopy cover  by 20
 percent will produce a 300 percent variation hi the predicted soil loss.

 Great importance should be placed on the accurate determination of the conditions within the basin.
 It is possible, and not too uncommon, to approximate values for some factors without actually visiting
                                            4.53                              September 1994

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            Environmental Issues      •                                    .     EIA Guidelines for Mining
                i                 >                                    i            „                      i
            a sice.  The SoU Conservation Service has made available tables and maps which provide probable   s
            ranges of values for various site conditions.  However, since the strength of a model depends on .the
            strength of input data, final determination of the factors to be used in a model should be based upon
                   ions	made	on	site.  Some important  factors affecting'soil erodability, such as the presence of
            thick leaf litter on a forest floor, are.not ^terminable from aerial photos or maps.  Any modeling
            performed without actual site observation should be considered a first approximation.
                {'            "     ,   ,    .         '    '      ,        •',,,,''     ,      !,"
            The final step in any modeling is verification.  A model should not be considered to have predictive
	I	!	|	>	!	 L   „'  ' 1	!   «"""   	 -	-!"  '  '.	 •	'•	!!'".'!',.	 ,	I!	|	'.',i	.;:" !'!"':.' '.',! *,,	
            power for hypothetical conditions until its ability to accurately model known conditions  has been ••
                  . * This means comparing actual measurements of soil losses with those predicted by the model.
           A great disparity between these two values indicates the need to examine either assumptions of the
         	model	or	the,	field	measurement techniques.
	The	Dejection	ofstonn	events	foruse	|n	modeling predictions should also be carefully considered.
           Since both	intensity .aid duration affect the generation of overland 'flow, both short duration/high
           intensity	storms	and	long duration/moderate intensity storms should be considered.  Also, antecedent
           conditions	at	a	site may be important.  High intensity storms win produce iigher peak flows and
             Sjijter	erosion	ratw tf Jhey_	fell, on	already saturated,'frozen, and/or snow covered soils.	
                            results .should allow die operator to quantify the impacts of the proposed land
                                              ...... ISlSESS ....... ojflosses ..... 2!,Si Eel 15!! §£?*„ and 'total solids
           loadings). However, available methodologies do not address deposition of generated sediments in
                               'there are no specific criteria to determine what level of increased TSS
          concentrations, turbidity, or total sediment loadings constitutes a significant impact.  To a large

                 this is subject to best professional judgment (in consideration of die baseline watershed
          ro|djtions	as	djscasse£iab£ye). Similarly, BPJ is necessary to assess how any toxic jrolhitants
          associated	with	solids	loadings could affect sediment quality, and this should-always be considered.
          Faoors	to^nsidCT	include:	potential	sources	of toxic pollutants, existing sediment  ualit, an
        \	 available	data	on	the	affects	of similar	operations/land disturbance within the watershed (where
        ^Ijj^licaole^	aid	mTnatureTdeslgnated	uses	ofihe	receiving	^^	•	

                   j^nvpOTAM&PsjpNMITIGATIONMEASURES
          Sediment and	a^jon^njitigtion	measures	are	used	to	reduce	the	amount	o^materials	earned	og^sitg	
          and deposited jn a receiving stream. To meet this objective, mine operators should consider methods
	»'	'"	to	limit	runon,	mjnimige^tfae	areas	^disturbed soil	(exposed to precipitation), reduce runoff velocity,
          and remove sediment from.on-site runoff before it leaves die site.  In many cases, a range of different
          BM^/sediment	ancj^	gosion	co^rolg	arg.used	gncurrentl^ a£ mine sites. The three main gategpries
          of sediment and erosion controls are: diversion techniques, stabilization practices, and structural
          controls. The following subsections briefly describe each of diese categories.
     I iililil	  -
                                                        4-64                              September 1994
                  lllllll Illlllllllllllllllllllll 111 llllll|lll|ll IIIIIIIIIH I lllllll 111 III  I"! IIIIIIIP       lllllll 111 II III 111 I III'111 III 111 111 HI I 111 III I II III IN Illlllllllllllllllllllll lllllll III1! I III llllllllllllll 1111 Illlllllllllllllllllllll lllllll I ll I ill lllllll 111 i|il|  I Illlllllllllllllllllllll Illllllll
                                                                  	'	I	!	

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  ~E3A Guidelines for Mining	                        Environmental Issues

  4.5.5.1    Diversion Techniques

  Diversion techniques are measures that prevent run-on, precipitation, and other flows from crossing
  areas where there is a risk of significant erosion.  Diversion practices often use on-site materials, and
  take advantage of on-site topographic, vegetative, and hydrologic factors to divert flows away from
  disturbed areas/soils.  Typical diversion practices used at mine sites include: interceptor dikes and
  swales; diversion dikes, curbs and berms; pipe slope drains; subsurface drams; and drainage/storm
  water conveyance systems .(channels, or gutters; open top box culverts, and waterbars; rolling dips and
  road sloping; roadway surface water deflectors; culverts).

 4.5.5.2     Stabilization Practices.

 Stabilization, as discussed here, refers to covering or maintaining an existing cover over soils.  The
 cover may be vegetation, such as grass, trees, vines, or shrubs.  Stabilization measures can also
 include nonvegetative controls such as geotextiles (matting, netting or blankets), mulches, riprap,
 gabions (wire mesh boxes filled with rock), and retaining walls. These stabilization practices act to
 prevent or minimize erosion by holding soil in place, shielding it from the impact of
 precipitation/showmelt, and increase surface contours to slow runoff velocity.

 The establishment and maintenance of vegetation is one of the most important factors in preventing
 erosion.  Vegetative controls  are often the most important .measures taken to prevent off-site sediment
 movement, and can provide a six-fold reduction in the discharge of suspended sediment levels.  In
 addition, these practices can enhance habitat values and the appearance of a site.  Examples of
 vegetative practices include temporary or. permanent seeding, vegetative buffer strips and protection of
.trees.  Nonvegetative stabilization practices can be used as a temporary or permanent erosion
 prevention measure.  These controls can be used hi order to aid in establishing vegetation or as stand
 alone practices.           '                                                                       .

 Vegetative controls are low cost and require low or no maintenance once a ground cover has been
 established.  However, prior to the establishment of a vegetative cover, considerable site preparation
 may be necessary such as contouring of disturbed areas, placement of tbpsoil on barren areas, soil
 conditioning (e.g., with municipal sewage sludge), or spraying areas with fertilizers.

 Contouring refers to a number of practices including recontouring, regrading, reshaping, and surface
 roughening.  Contouring of waste piles will provide a number of benefits, including aiding hi the
 reduction of storm water and run-on velocities, assisting in the establishment of a permanent
 vegetative cover, and improving site aesthetics.  Specifically, reducing the height and steepness of a
 slope can greatly reduce erosion and sedimentation at a site.
                                              4-65                              September 1994

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            Environmental Issues
                                                                                EIA Guidelines for .Mining
     i iii iiiiii
      inhere recontouring wastes is not practical due to geographic or resource considerations, reshaping of
1111111111	wasS	may" be a viabie option.  Reshaping BMPs refer to the rearranging of waste piles and exposed
                                                                ig/benching), moving waste piles out
               I
	areas	in	such	a	wajr	as	to	reduce	the	steepness of sloges
            of speambeds or other highly credible areas, and other methods to reduce nates andstonn water
            velocities over and around areas susceptible to erosion.
                                                                                   II n in in i| inn 111 in n in ill
    Ill	      After an area has been recontoured or reshaped, surface roughening may be employed to further
    i ijiiiiiiiiiiii   inn  I    	SB	*	;	*	"	"	        <
            reduce nmpff.yelqcjty^and promote infiltration, as well as supporting revegetation. A rough soil
            surface is amenable to reyegetation, through creation of horizontal grooves, depressions, and/or
           terraces that parallel the contour of the land.
           4.5.53    Structural Practices
                                                              III 111 Hi in  I III i II ill III i
                                  *                         "                          'II
           Structural controls involve the installation of devices to store flow or limit runoff velocity.  Structural
           practices can be used to remove sediment from runoff before the runoff leaves the site.  Approaches
                                II                                               II f       I       *^-;	|!	
           to removing sediment from site runoff include diverting flows to a trapping or storage device or
           filtering diffuse flow througjisflt fences before it reaches the receiving water. These methods are  .
           designed to slow the flow of water discharged from a site; resulting in the settling of solids and the
           limiting of downstream erosion.  Structural controls also promote infiltration.
                     i                                                          .                 •
           StruGtoral sediment and erosion control practices are typically low in cost.  However, structural
           practices require periodic maintenance (including sediment removal) to remain functional. As such,
           they serve as more active-type practices which may not be appropriate for permanent use at inactive
           mines.  However, these practices may be effectively used as temporary measures during active
           operation and/or prior to the implementation of permanent measures.
          Some examples of structural practices include: settling ponds/detention basins, check dams, rock
          outlet protection, level spreaders, gradient terraces, straw bale barriers, silt fences, gravel or stone
          filter If1™3' brusb; baf^|eis' sediment traps, grass swales, pipe slope drains, earth dikes, and other
          controls such as entrance stabilization, waterway crossings or wind breaks.
                 i i          •    ii      I                          i              i

                                i           »   •     .
          In some cases, the elimination of a pollution source through capping sources of erosion may be the
          most ..... pst ...... ejffiKjtive^control ...... measure, ...... for. ...... sediment, ...... discharges and other pollutants. Depending on the
          type of management practices chosen, the cost to eliminate the pollutant source may be very high.
          Once completed, however, maintenance costs will range from low to nonexistent.
          4.5.5.4    Contact Prevention Measures/Reclamation Practices
               |                 '               '      	"	   '        '
          Permanent reclamation, as discussed here, refers to covering or maintaining an existing cover over
          disturbed areas.  The cover may consist of grass, trees, vines, shrubs, bark, mulch and/or straw.
                                                      . 4-66	September 1994

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.  EIA Guidelines for Mining        .    •       •                          •   Environmental Issues

  Ultimately, revegetation involves establishing a sustainable ground cover at a site through permanent
  seeding, mulching, sodding, and other such practices.

  The establishment and maintenance of vegetation is one of the most important factors in minimizing
  erosion. A vegetative cover reduces the potential for erosion of a site by:  absorbing the kinetic
  energy of raindrops which would otherwise impact soil; intercepting water so it can infiltrate into the
  ground instead of running off; and by slowing the velocity of runoff to promote onsite deposition of
  sediment.  Vegetative controls are often the most important measures taken to prevent offsite sediment
  movement, and can provide a six-fold reduction in the discharge of suspended sediment levels. In
  addition, these practices can enhance the habitat and aesthetic values of a site.

  Typically, the costs of vegetative controls are low relative to other discharge mitigation practices.
  Given the limited capacity to accept large volumes of runoff, and potential  erosion problems
  associated with large concentrated flows, vegetative controls should typically be used in combination
 .with other management practices. These measures are universally considered to be nearly always
 appropriate for mining sites, as evidenced by their being required by ail States that require
 reclamation of closing coal and non-coal sites.

 As noted above, vegetative controls are low cost  and require low or no maintenance once a ground
 cover has been established. However, prior to the establishment of a vegetative cover, considerable
 site preparation may be necessary such as contouring of disturbed areas, placement of topsoil on
 barren areas, and the spraying of areas with fertilizers.  Further, predicting the  likely success of
 reclamation practices at mine sites has often proven difficult.   Where reclamation/revegetation is a
 key element of long-term erosion control, the operator should consider establishing representative test
 plots to increase the likelihood of success.

 Contouring

 Prior to the establishment of vegetation, surface contouring is  often required. Contouring refers to a.
 number of practices including recontouring, reshaping, and surface roughening.

 Recontouring waste piles/disturbed areas at a site will provide a number of benefits. Recontouring
 wastes or disturbed areas to match the original land contours of a site will aid in the reduction of
 storm water and ran-on velocities, assist in the establishment of a permanent vegetative cover, and
 improve site aesthetics.  Reducing the height and steepness of a slope, combined with other diversion
 BMPs discussed above,  can greatly reduce erosion and sedimentation at a site.  This practice is also
 often times necessary to establish a vegetative cover over exposed materials.

 Where recontouring wastes is not practical due to geographic or resource considerations, reshaping of
 wastes may be a viable option.  Reshaping refers to the rearranging of waste piles and exposed areas


                                              4-67                              September 1994

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                            •••^^    iiiiiiiiiiii iiiiiii iiiiiiiiH^           mi 11 ii mi 11 in iiiii i in  i	iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii       •    mi i iiiiiiiiiii in ill 11 11 nil i i in 111 MI i  mi in  11 ill mi i iiiiiii||i|i  11 |ii in 11 i in i in iiiiiii
              Environmental Issues	      '	          EIA Guidelines for Mining

              in such a way as to reduce the steepness of slopes (terracing/benching) and other methods to reduce
              rmi-on and storm water velocities over and around areas susceptible to erosion.

              After an area has been recontoured or reshaped, surface roughening may be employed to aid in the
              establishment of vegetation.  A rough soil surface is amenable to revegetation, through creating
            I	tejgfijSS grooves, degressions,	or	steps.that	run	with	the	contour	of the	land.	Slopes may also' be
              left in a roughened condition to reduce discharge flow and promote infiltration.
                      . -  ,    J, •        :                 "      •                 ,          '"'.'.
                     roughening aids in the establishment of vegetative cover by reducing runoff velocity and
                    seed an opportunity to take hold and grow.  Increased vegetative cover, in turn, provides
                          •ation and sediment trapping, farther decreasing runoff velocity and erosion.
                   techniques are appropriate for all slopes steeper than 3:1 in order to facilitate stabilization of
                                              9? ? yfS?!3*!}^	PPYer. .Pncfrareas	have	been,,,,con|oured, they'
                                                             -
            Topsoiling          '     •                                                            ,
•H         	ilUIEII^^              111, Illlllilllllllllll              lllliillllllll Iii!!', III!	1 liillll 1	IlililH^    HI ,. II	ll'l'lli II1   ' lllliillllllll IlllllW^^^     	lilllliillilill'lllilili'i Win^^ IIP!1 II IIIIIII IT I	••illH	1" I	I	 nflll! i Iiiii1 "linlili liillll 111!!	llllhil	II	Nil
                       may be necessary to improve,- provide, or preserve the area on which a permanent
                          _   _ *_ ____,_^  ifa^ practices ^ ^ ^^J £OD& tQ pjovjdg erosion' control,
                                  [[[ i [[[ ii [[[ * ,     ........    ,    ,  ™
           ...... ^ ........................... il [[[ Mjj.. [[[ i ......................................... [[[ i [[[ ii [[[  ,     ........    ,    ,
           1*9? :,«re an mtejral part of establishing vegetative controls. Conditioning may be required where soil
            & oCpoor quaUty. More resource intensive topsoiMng measures may be needed where soils are
                                       ....... where ..... the ..... need to ..... quickljr ...... establish^ vegetatira is paramount, where tbe
                         ....... Snt5n| ..... maieriS ...... trade ..... to plant g^^ (i-e^ acidic sofl ^jj -^
                            : the soil rooting zone is not deep enough to support plants.
                                                   liillll1 llh Ililliililliiii 41
            _ S_22!21	23	,S£!2J!e,	*£	W* ?f fertilizers, or less ejq)ensive-measures such as the land
                      •	SliSiSSiJSlS!,	22S	Si!?80'  Usm£ toPs°a n^y require the importing of soils from an
            alternate location or the use of soil from a nearby site.
                           soSSfSfers^or	topsoil, measures must be put hi place to prevent washouts prior
                                                   ***$*& of this practice should be coordinated with seeding and
                   I	g22iSi	52	£2	S2	22	£S Performed immediately after soil conditioning or topsoiling is
                   ed.  Additionally, it is necessary to provide measures such as mulching or diversion which
           prevent erosion of the topsoil or conditioned soil. These practices should be coordinated with seeding
           and planting practices so that they can be performed immediately after conditioning or topsoiling.  .
                                                                                             i
                  "


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 EL4 Guidelines for Mining	Environmental Issues

 Seeding

 The establishment of plant life stabilizes soils and helps to reduce sediment in runoff from a site. In
 addition, vegetation filters sediments, maintains the soil's capacity to absorb water, improves wildlife
 habitats, and enhances site aesthetics.

 Seeding and planting are appropriate for any disturbed area mat is subject to erosion. This practice is
 particularly effective in areas where soils are unstable due to texture, structure, high water table,
 and/or high slope such as those commonly found at inactive mining, landfill, and oil and gas sites.

 Selection of appropriate vegetation, good seed bed preparation, timing, and maintenance are needed to
 ensure the success of this practice. Selection of native species will increase the chances for success
 and may lessen future maintenance requirements.

 Capping of Wastes/Materials

 Capping/sealing of wastes/materials (including surface mine workings, tailings and waste rock) is
 designed to  limit or eliminate contact between runoff and potential sources of sediment/toxic pollutant
 loadings.  The use .of this practice depends on the level  of control desired, the materials available, and
 cost considerations.  Many common types of caps may be effective including soil, clay, and/or
 synthetic materials. Generally, soil caps will provide appreciable control for the lowest cost. Any
type of cap may be covered with up to several feet of rock and soil and revegetated.

4.5.5.5    Treatment Techniques   .

Discharge detention structures can achieve a high removal rate of sediment and metals, such as those
which may be expected to be discharged from inactive mining operations.  Complemented by ease in
construction and simple operations and maintenance, the use of detention structures desirable as a
treatment mechanism for discharges from inactive mines and landfills. Site characteristics must be.
such that discharges can practically be channeled to a centralized area for treatment.

 Detention basins are most cost-effective at larger sites.  In addition to their pollutant treatment
 capacity, detention ponds can also create wildlife habitat, recreational, and landscaping benefits.
Even at larger sites, however,  hydrologic and topographic factors, as well as inaccessibility and cost,
may limit their utility.

 4.6     METALS  AND DISSOLVED POLLUTANTS

 Dissolved pollutants (primarily metals, sulfates, and nitrates) can migrate from mining operations to
 local ground and surface water. While ARD can enhance contaminant mobility by promoting
 leaching from exposed wastes and mine structures (see Section 4.1),  releases can also occur under
                                             4.59                               September 1994

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  Environmental Issues
                                                                     EIA Guidelines for Mining
         pH
                       s.  Primary sources of dissolved poUutants from coal and metal mining operations
           J   ...*    d^S^aceimne workings; overburden and waste rock pUes; tailings piles and
    impoundments; direct discharges from conventional^inilling^eneficiatiQn operations; leach piles and
    processing faeiliaesj coal processing units; chemical storage areas (runoff and spiUs); and reclamation
    actiymes.  Discharges of process water, mine water, runoff, and seepage are the primary transport
              ; to surface watei- and groundwater.
:-	1=	I	,	
 One potential
                                    ?*!?§* » chemicals	used in mining and beneficiation.  Common
                                    " ^ogriuoi,cyanide, nitrate and phenolic compounds, along
                  -"T*«-T	-»-Perations.  With the exception ofteaching operations and
  :iSli	Si	         	II	rfsfeo&Saaeqoafc in blasting and reclamation, the quantities of reagents
  ** ***W ^ Con9)ared to ** volumes of water generated.  'As a result, the risks from releases
          DOlllltanf frnm nnn-1p*>r>hinCT_ra1a+asf «»•>»<...*..	ti  «••...,_.
                                                                     (see Sections 4.1  and 4.2
	of toxic jjwUutant	from
««««««««~ii|««««««u«««««
  fo
                                            ,    .
                                         regents are generally .
                                 [[[ *^ -- - — JP~ '"••*«***J ***!*•» W»* ^OWW OW%
              ...... of the potential impacts associated with acid and cyanide releases).
A major source of poUutants is naturaUy occurring substances in the ore: Mined ore not only
con**™* A* mfn^.1feeing extracted but varying concejaratioisof a wide range of other minerals
                      ' iOPbegesentatmuch higher concentratipns and can be sigtiificantiy
                               ^
                   	»SBS	35«Sfi:	Depending on the local geology, the ore (and the surrounding
                          on include trace levels of aluminum, arsenic, asbestos, cadmium    '
          £°PP«r. iron, lead, manganese, mercury, nickel, sUver, selenium, and zinc.
                                                                                                       •

              of specific poUutants, their release potential, and the associated risks are highly
            facility-specific conditions, including: des'ign and operation of extraction and
                 "ons' waste:SSl	SlSiiSli:=iiiiiagen^ practices, extent of treatment/mitigation
                                          climate, geology, hydrogeology, waste and ore
          	—'	          ™-   *-w *  ^	^— —-— £jj 9 **«AM»«r MII^I WA5
          j^t*^**?*0*' ?te->.^JI9?«B °f and proximity to human and environmental
            "  development of the National effhient guidelines for me Ore Mirung and Dressing
               ^ 5°Sce categories (40 CFR Parts 434 and Part 440), EPA conducted sampling
PIII ............. , »
                  iff*	12	Identify poUutants of concern at mining operations (focusing primarily on
                  f^f Trr^+A* *»rf%*.	^^  v«__* *•-.-.     	                                '
                                                                                  -
                            ....... SI .....        ............       ..... Mprovidesa summary of the metal pollutants
                         operations.
                  with discharges from specific types of hardrockMoiwoal mining operations
                         ...... IP«ices).  Exhibit 4-5 describes dissolved pollutants often found in
                    a presented in the tables were primarily obtained from sampling of mine
                              ,Eastewatera	WMh,	the	exception of coal and refuse pile runoff at

iiiili i:l,',:,i! „ " i: , ,!,:!!; V ' • , •; •

i 	 • 	 : 	 - 	 - 	 ii: 	 	 	 ir

iiliill il "". '•! 1",:1, „,„ ' , Hi" '!' li,:1' , , ';•, • 1, |i , •,
	 ! 	 i 	 , 	 ; 	 	 L; 	 ijli 	

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  EIA Guidelines for Mining
Environmental Issues




Exhibit 4-4. Typical Pollutants Associated With Hardrock Mining Operations
Type of Mining
Iron '
Copper, Lead, Zinc, Gold,
Silver, and Molybdenum
(excluding cyanide leaching
operations)
A iiifTf {(Vim
Tungsten
Mercury
Uranium
Antimony
Titanium
Vanadium
•Potential Pollutants of Concern in
Discharges to Surface and
- " Gnmndwater
Asbestos, arsenic, and copper, iron
Aluminum, antimony, arsenic
cadmium, chromium, copper, lead,
manganese,, nickel, thallium, and zinc
None found at high concentrations
Copper, lead, and zinc.
Most .toxic metals
Radium 226
Antimony, arsenic, and asbestos
Most toxic metals
Mercury, arsenic, ga^mmm
chromium, copper, mercury, lead
and zinc
Typical Treatment :
Sealing ponds and flocculation.
Recycling/reuse and
settling/precipitation ponds
Not Applicable
Recycle (mines have generally been
located in arid regions)
Evaporation ponds and/or
recycle/reuse
Evaporation; ion exchange;
flocculation; settling; and
recycle/reuse
Recycle/reuse
Settling and precipitation
(lime/caustic addition)
Neutralization, settling and
precipitation
Source: EPA, 1982; ore mining and dressing development document.



Further, they have historically not been subject to the same level of control/treatment as mine and
process wastewater.

In assessing the nature and extent of potential dissolved pollutant releases from new source raining
operation, reviewers can often supplement general information (such as the above tables) with site-
specific data.  This wfll include information on local geology (focussing on the chemistry of each
geological unit and the likely composition of wastes/exposed materials).  In addition, mining
operations are often located in historic mining districts.  Where this is the case, significant existing
data may be available (or collected under baseline monitoring) to describe past releases to surface
water and groundwater, how they have affected me environment, and the  effectiveness of current
treatment/control measures. It is not uncommon to find naturally occurring levels of metals and
sulfates (particularly iron and manganese) in highly mineralized ground and surface water. However,
rnining and land disturbance activities have the potential to increase the loadings and mobility of
specific pollutants.
                                             4-71
   September 1994

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        I'llilillll
      illllil
Illllli lilll
           Environmental Issues
iilllllllfl!l!il|lllVll ..... Illlliiilii ' ill lllllin liillll ...... 111!! ...... Ill ..... llilii ...... ! ........ r [[[ i [[[ . .......

      .       _ EIA Guidelines for Mining
        I HI 111 111 III IIH
                      Exhibit 4-5.  Typical Pollutants Associated With Coal Mining Operations
';- , ;'.•'. ': V,
Wasfewaier Type
Coal preparation plan:
wastewater
Coal pile runoff •
Refuse pile runoff
Anralfjxf rnntf tfrajnage (see
Section 4.1 lor discussion
of acid mine drainage)

Potential PoDntants of Concmrin
. Discharges; to'Surface. and.:
'- *\ : • Groundwater
Arsenic, cadmium, copper, lead
silver, and zinc.
Manganese, iron, arsenic chromium
copper, lead, mercury, nickel,
selenium, and zinc
Copper, cadmium, .silver, and zinc
Iron ajvj Tnrmtjanese

F ' .
Typical Treatment
Settling and precipitation,
recycle/reuse


Neutralization and precipitation
Neutralization and precipitation
llllllltilllllllllllllllllllllllllllllllllll'HIIIIllllllllllllllin^ ..... Wwwh
                                  Htow provides information on the acute and chronic impacts of dissolved
       "Pollutants in surface water @r«luding suggested water quality standards).  Each State has promulgated
        -**{* quality criteria for surface waters based on the designated uses of the waters as well as
                                            	        "" "     ' '        '!	  "  .   "• 	
                                      to apply the standards. Reviewers,should be cognizant that, unlike
                                     operations ...... 2*1 ...... discharges, ....... there ...... can ...... be ...... extreme ....... variability in toxic
        coriuent ..... oadngs from mining operations, both from day to day and over months and years.
                             ™               ticrfarfy ..... sensitive ...... to ...... loadhigs of toxic pollutants during
4.1 and 4.5, ta$donal
                                     and analyses-during these critical periods. _ As discussed,, m Sections,,
                                       or
                                            d
         programs may not provide for sampling
 jnost	advene	,131)3018 on surface water quality.
                     utants discharged to surtace waters can partition to sediments. Specifically, some toxic
        constituents (e.g., lead and mercury) 3550^^ ^J£ disdjajg^ '"^^ mining operations are often
        found ^	f!22£!	!5!S!$	™	SSSESS.:,	,2Se,	12!	SgSS	detected^	in	the,	water column.	Sediment
        contamination may impact human health through consumption of fish that bioaccumulate toxic
        poUlfaj11!:	!!E!!S!	flSS!	!22!£	2!,|°SE Po«utantsi in sediments can haye direc|^,,a"cute;and chronic
                   macromvertebrates and other aquatic life. Finally, sediment contamination provides a
                ,	222	ofpogutante	trough	|wtential	redjssolutipn	in	the	water	colurnn,	As	note^	in
        SectiPn 4,:5i §S| SS SSI^y "o national sediment standards/criteria for toxic pollutants associated
        with rruning operation (although EPA is in the process of establishing criteria and partitioning
        techniques for toxic metals). Reviewers must typically rely on BPJ to  determine  the sediment impacts
        from new sources.
                                                     4-72
                                                                                September 1994

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 353A Guidelines for Mining	                           Environmental Issues

 Finally, the ability of pollutants to dissolve and migrate from exposed materials/waste management
 units to groundwater varies significantly depending on the constituent of concern, the nature of the
 material/waste, the design of the management unit, soil characteristics, and local hydrogeology
 (including depth, flows, and geochemistry of the underlying aquifers).  Potential risks to human
 health and the environment from contaminated groundwater usage are a function of the types of and
 distance to local users. In addition, impacts on groundwater can also indirectly affect surface water
 quality (through recharge and/or seepage). At some sites, the potential for groundwater
 contamination may be limited to alluvial aquifers which have limited beneficial uses but are significant
 source of recharge.  Section 4.5.1 describes elements to consider in performing baseline and long-
 term groundwater monitoring!

 4.7    AIR QUALITY

 The primary air pollutant of concern at mining sites is paniculate matter. As noted in Chapter 5,
 particulates with a diameter of less than 10 microns is one of the air pollutants for which EPA
.established National Ambient Air Quality Standards. State Implementation plans must ensure that
 paniculate emissions from whatever source are controlled sufficiently to allow attainment of the
 ambient air standard and to meet opacity requirements.
                                    •  _            .                 •                      •   '   v
 Particulates are emitted from a variety of mining operations, usually as fugitive dust (as opposed to
 emissions from stacks),, and relatively simple controls are typically sufficient:

        •     * Ore crushing and conveyors can be a substantial source of fugitive dust, and control
               generally involves water sprays or mists hi the immediate area of the crusher and
               along conveyor routes.

        •      Loading bins for ore, limestone, and other materials also generate dust. Again, water
               sprays are typically used.  .                                                    .

        •      Blasting generates dust that can be, and sometimes is, controlled with water sprays.

        •      Equipment and vehicle travel on access (and haul roads is a major source of fine and
               coarse dust. Most mines use water trucks to dampen the surface periodically.

        •      Waste rock dumping can generate dust, but this generally consists of coarse particles
               that settle out rapidly with no other controls.

        •      Wind also entrains dust from dumps and spoil piles, roads, tailings (either dry as
               disposed or the dry portions of impoundments), and other disturbed areas.  Spray
               from water trucks are often used when the mine is operating.  During temporary
               closures and particularly after the active life, stabilization and reclamation are aimed
               in part at reducing fugitive dust emissions. Tailings in particular can be a potent
               source of fine particulates. Rock and/or topsoil covers, possibly with vegetative
               covers, can be effective controls.
                                             4-73                               September 1994

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      •ill 11
          "	Environmental Issues
                                                                 i   •           'iii
                                                                                  EIA Guidelines for Mining
I Illllllllllllllllllllll  •ill iillllB  IIIIIIIIIIIIIIIIIIIIIH^         Illllli^   Hi 1*111 Illllll Illllllllll i Illllllllllllllllllllll IIIIIIIIIIIIIIII ill ii III IIIIIIIIIIIIIIII ill Illllllllll IIIIIIIIIIIIIIII IP HI Illllllllll 1111 Illllllllllllllllllllll ill lllllllllllllIB  llllllililllllllllll Illllll
         As discussed in various sections above, tailings and waste rock at
tm	im	S"J	"	^^
                                                                                                 contain trace
            concentrations of heavy metals.  Fugitive dust would also contain such metals, and areas immediately
            downwind could accumulate troubling amounts of dust as coarse particles settle out of suspension hi
            the air.
         •i!	iiiiii'iiiii iiiS            	j«!L 	'	i	;	'	'	'	i	'	'''""'	'
            *   '                                                              '
            *& addition, on a few occasions, wind has caused,cyanide sprays on heap leach piles to blow short
            distances and caused very localized damage.  For this reason, more operators are turning to drip
           " application of cyanide solutions.
           4.8    SUBSIDENCE

                                                           SSlS ...... 251 ...... 2SSS ..... SS ....... a ..... r,S§ult ....... of the collapse of
                     strata	intpjnine	voids.	JThe	potential	for •subsidence exists for all forms of .underground
                     Subsidence	.may	manifest	itself_m	the	form	of sinkholes or troughs.  Sinkholes are usually
                          	tit	fiofiapse of a portion of a mine void (such as a room in room and pillar mining);
                            	^                *        •
               extent	of the	surface	disturbance	is	usually limited hi size. Troughs are formed from the
                               portions of the underground void and would be typical over areas where most of
                            been removed (Singh and Bieniawski, 1992).
                                 of snjgdence ..... i§ ...... SMsI ...... ISJfeg ..... njejipd of mining employed.  In many mstances,'
                 ......    ......                    ..... ......       ......      .....
       traditional ...... room ...... and pillar methods leave enough material hi place to avoid subsidence .effects. '
                                                              iUar ...... retreat ..... and ..... longwall mining result hi a
                                                                 ieier, 1990; Britton, 1992).
                                                                       U        I            *
• ...... ' ............................. " ................. ' ' - ....... 'strong likelihood that subsidence wfll occur
                                         "
        ••• Iiiiiiiiiii
                                  1111	1
                              [[[              ...                 ......      ..........
                           operations typically consider subsidence'm the planning process.  Two approaches
                  taken to addressmg the problem: planned subsidence or planned subsidence prevention
          (Britton,  1992). The approach can be governed by the type of mining activity planned or by the
          degree of severity of subsidence impacts.
          Planned subsidence involves predicting the maximum area! extent and depth of ground lowering
          induced by the proposed mining activities. Thls.prediction can be used to develop surface mitigation
          n«asu^ or appropriate modffication of surface land uses in response to the subsidence.  Typically,
          subsidence will occur within a few weeks after the mining face passes under an area although it may
                                                 Pletel  settle-
iiiii in 1111
iiiiiniUiiiiiiiiiii
          Subsidence prevention involves leaving supports (pillars) hi place following mining activities to
          prevent subsidence from occurring. In this approach, factors governing subsidence are also analyzed
          2 ..... ISJ ..... ! ......         ...... igS3ff,,£,,2le, ..... SSS,S?y ** Amoved while leaving enough material (either the
         ........ RSffi ...... ffiiSSiS! ....... JS, ,ftlace to prcveiK subsidence.  A combination of the planned subsidence and
       llllll Illllll ..... Illllllllllllllllllllll Illllll HIM
         lil in1 ..... 1 llllllliilP !
111 lllllH III IIIIIIIIIIIIIIII 111 III II Illllllllll IIIIIH^^^^  Illllllllll I Illllll III II Illllllllllllllll 111 II 111 Illllllllll 111 1 111 1111111 Illllllllll 1
 IIIIIIB  ' ..... 1 li ..... IN Illllll ..... llllili ...... I llillllil •ill III ..... 1 ........ 1 liliiil ..... Ili'i illlilll11 111 ...... Ill ...... "ill V 111 ....... Illlliii
                                                                                  lllllllllllB          111 II 111 111 Illllllllll I Illllll 1 1 III IIIIIIII
                                                                               ..... Illllllllll IIH^^^^^      (111 ..... Ill1 1 ' 111)
                                                                                                                    "
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•iiiii iiiii i iiiiiiii  i in n
iiiiiiiiiiiiiiii	iiiiii iiiiiiiiiii
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                               n n iiiii i in i   i mi in n i n iiiiiiiiiiniiiiiiiiiii • iiiiiiii in
                               Iiiii 1111 Illllllllll 111	llllllililllllllllll Illllllllll	
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                                                 I INI III
                                                 lil illlilll1 1
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                                                         4*74
                                               i iiiiiiiii iii i in i ii iiiiigii iiiiiiiiiiiiiiii iiiiiiiiin i n i in iiiiiii i iiiiiiiiiii iiii|iiiiii iiiii in iiiiinn iiiiiii 11 in in i ii in iiiiiiiiiiiiiiii in i  i   i
                                                               September 1994
                                                 i      i       I

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  EIA. Guidelines .for Mining	Environmental Issues

  planned subsidence prevention approaches could be used in cases where some surface features require
  protection while most of the overlying area do not.

  The subsidence that occurs hi areas overlying abandoned mines is referred to as unplanned
  subsidence. These mines, hi many cases, lacked any overlying development and were operated
  without concern for subsidence.  Unplanned subsidence can also occur hi association with more
  modern mining operations, arising when subsidence is not considered hi the development of the mine
  plan, or hi the event of .an unpredicted occurrence (i.e., roof or pillar failures, groundwater inflow).
  In these cases, the depth and extent of surface.disturbance cannot be (or is not) determined.  Likewise
  the time frame for the occurrence of subsidence cannot be predicted.

  The extent of subsidence depends on the thickness of the seam (or deposit) mined, the amount of coal
  (or ore) left in place or the amount of backfill placed hi the void, the nature and thickness of the
  overlying strata, the depth to the void, the permeability of the overburden to water, and the presence
  or absence of groundwater. The area potentially affected by subsidence extends beyond the area
  directly above the mining void; these effects to the adjacent lands extend into what is termed the angle
  of draw.  The angle of draw extends 15° to 30° from the edge of the mining void outward (McElfish
  and Beier, 1990, Singh, 1992).                            •

  Effects of subsidence may or may not be visible from the ground surface.  Sinkholes or depressions
  hi the landscape interrupt surface water drainage patterns; ponds and streams may be drained or
'  channels may be redirected. Farmland can be impacted to the point that equipment cannot conduct
  surface preparation activities, irrigation systems and drainage  tiles may be disrupted.  In developed
  areas, subsidence has the potential to affect building foundations and walls, highways, and pipelines.
  Groundwater flow may be interrupted as impermeable strata break down, and could result hi flooding
  of the mine voids.  Impacts to  groundwater  include changes in water quality and flow patterns
  (including surface water recharge).

  The Bureau of Mines has estimated that of the seven million acres of land underlain by underground
  mining, two million have been affected by subsidence (McElfish and Beier, 1990). SMCRA requires
  that underground coal mining operations prevent subsidence from causing material damage to the
  extent technologically and economically feasible or, to employ a mining method which provides for
  "planned subsidence hi a predictable and controlled manner."   Regulations governing  subsidence from
  non-coal mines is dependant .on the individual regulatory, authority responsible for those operations.

  4.9     METHANE EMISSIONS FROM COAL MINING AND PREPARATION

  The biogeochemical processes  known as codification give rise to the formation of methane (natural
  gas) and other gases which remain closely associated with coal hi virtually all coal-bearing
  formations. Adsorbed to surface sites within the highly fractured coal matrix, methane typically


                                              4.75                    .          September 1994

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                               k                                                         .
            Environmental Issues  .	  EIA Guidelines for Mining
   ,4         constitutes only a small fraction of the total energy content of the in-place coal.  Within the
            formation, methane remains bound to surface sites in a monomolecular layer under the influence
       	iliiiiSi!	I formation pressure.  However, under reduced pressure conditions resulting from mining,  water draw
,!	,	|£"|&	2S	22SlSa' methane desorbs from coal and becomes	free to migrate within and beyond the coal
  •in111 tirmm	
  Illllil  IIIIH^^^^
                                                                         "   •         I
           Miners have long known of the release of methane from mined coa|; methane is responsible for some
           of the worst mine explosions to have occurred in this country and elsewhere.  Accordingly, coal
           mining operations always include substantial ventilation equipment to maintafo airborne methane
               | I          (I    '             l   l l   "  I    I"! 	 i  	•  	'	,	i	i	'	Shi
           concentrations below one or two percent. Typically the vented air is released directly to the
         ,  atmosphere, though hi some instances an effort has been made to collect and compress the methane  •
          '                                     '
            	,	s	2SS	SSSSS	£°.m».H2f'	555	J?.	sixSSRSi.Sl.SSi.	Curing extraction operations
           raisesa number o.f environmental issues, both local and global. In particular, current political and
           	,_,,.,,==,	.concern	oys,,fe. prospect of global warming associated with the release of greenhouse gases
           ...i;;;;;;;;;;;;;;;;;;;;;;;111!^!	"" i  i   ' i	 i	«   	i   ». "II i "  .     '"i       i i J1 '  * in  n ' I1 i     i  '   * '    	  i  ||	 Sr	 »
           to the atmosphere has focused an increasing amount of attention on the role of methane in radiative
          'Qf&Pii ^^^ k a S5!5§l IF®?^0!?? g35 with a radiative forcing potential of 30 to 55 tunes that
           Of csEbon dioxide *  Because methane's estimated contribution to the total atmospheric radiative
           _   j i  : i       /'"i1 '!   '.LI. '        '    .   ..    n           ,n  i   .  . '.  ,    ',,i  ,   u*7 . M,	,   IN	    M
           forcing	associated	with	industrial	emissions	is	significant, and'because at least some of those
                                          and profitably reduced, such emissions from coal mine
                    tion may warrant consideration as incremental or cumulative impacts associated with coal
         • mining.
                                                 ,                                         	!/!,       ,
                                                                      .  '                              '
                                                                                       :M!1H^^
                                                                                 emissions associated
        	^roximately 7-12 percent of annual	methane	emissions	from	all	U.S.	sources.	Mejhane, jslreieased	
        	during degassification of operating mines	(78	percent	of releases),	during pre-mining coal seam
        	degassification (18 percent), and duriig	cod	grep^aration	(4 percent).  Further, due to mcreasing
          methane concentrations hi coal with depth (due to temperature and pressure), an estimated 88 percent
          of al^ methane releases from coal mining and" use results from underground coal, with the remaining
          12 percent attributable to surface-mined coal.

          As a practical matter, few or no mdmdual,|mines	could	to	expected	to	release	sufficient	methane to
          constitute a significant impact on the	gjobaj	attnosj)heric	methane	budget. However, i the importance
       "':	2fj£ef	223! Potential impacts of greenhouse gas emissions make it ^propriate to examine methane
                                                            and ii
              I	
                                                      4-76                             September 1994

    	illliill	I	Ill	Illilli	

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 EL4. Guidelines for Mining                                              *  Environmental Issues

 More locally, some of the technologies associated with pre-mining degassification may have direct
 surface impacts similar to those associated with oil and gas exploration and production activities.
 Specifically, wells closely resembling conventional gas production wells may be completed into the
 area directly above long .wall mining panels several years in advance of mining for the purpose of
 removing (and recovering) methane from the coal seam.  The wells are designed to draw down
 formation water pressure allowing methane to enter the gas phase and flow to the well.  Under
 favorable conditions, methane may be recovered in sufficient quantities and under sufficient pressure
 to allow onsite use or pipeline sale. In fact,  coalbed methane development projects  have grown
 dramatically in number since the early 1980s, particularly in areas where coal is too deep to mine
 economically.

 Coalbed gas development wells typically produce substantial quantities of formation water along with
 the gas.  Such water may be high in chlorides and other dissolved solids, and presents a surface
 management challenge. Additionally, drilling muds, workover and completion wastes, and other oil
 and gas associated wastes may be generated at the degassification site.  Any impacts caused by
 coalbed degassification prior to  or during mining could be considered as indirect effects of issuance of
a new source permit.  Accordingly, the effects should be assessed along with other cumulative
impacts.
                                             4.77                              September 1994

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                                                                                                                                                                                                                    '                                                   .....


                                                                                      H!!!!!!^                                                                  SEililS
                                                                '
                                                                                   ,]	IIIIIIIj^                              	ii	|i|.Hiliii;J«i,l	iSilllllii'V	Hi	!iii
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 EIA Guidelines for Mining                                                    Impact Analysis

                                 5.  IMPACT ANALYSIS

 This chapter describes specific NEPA documentation requirements and needs.  Where appropriate, the
 following sections distinguish among requirements that apply to EIDs, EAs, and EISs.

 In many ways, this chapter builds on information presented hi previous sections. Chapter 2 provided
 an overview of requirements 'for NEPA reviews of new source NPDES permitting actions. Chapter 4
 identified the key environmental issues and impacts associated with mining industry operations.

 5.1    DETERMINE THE SCOPE OF ANALYSIS

 "Scoping" refers to the process of determining the nature and extent of significant issues associated
 with a proposed action.  Scoping is a key preliminary step for all types of assessments, allowing the
 analyst to focus on what is most important.

 In the case of EIDs, scoping is an informal process. As part of an initial consultation between EPA
 and the permit applicant, the applicant should be prepared to explain why a permit for a new source
 discharge is being requested.  The applicant should be prepared to discuss the context for the permit
 application and to address such questions as:

     •   How is the action related to your firm's business or other objectives?              -

     •   How would the proposed new activities relate to any existing operations?

     •  What issues are thought to be important with regard to the new source permit (e.g., any
         additional employment opportunities or effects on the local economy, pollution, nearby
         historic or cultural sites)?

     •  What existing environmental or other studies or data would be helpful hi this review?

     •  Is the proposed new source discharge anticipated to raise any concerns within your
     •   Are any groups or individuals likely to be particularly interested in or concerned about the
         new wastewater discharge?

In preparing an EA on the proposed issuance of a new source permit, EPA will review information
provided by the applicant to help identify any potentially significant issues. EPA also will contact
representatives of any Federal, State, or local government agencies that may have a particular interest
in the proposed action. Among those agencies likely to offer information that may be helpful hi the
early identification of key issues are State mine land regulatory agencies and Federal land managers,
local land use planning agencies, the State environmental protection and natural resource management
                                             5_1                              September 1994

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	Impact Analysis
EIA Guidelines for Mining
            .agencies, and the State Historic Preservation Officer (SHPO).  Contact with Regional representatives
             of the U.S. Fish, and Wildlife Service and the National Marine Fisheries Service can be helpful in
             early identification of any potential issues relating to federally listed threatened and endangered
             species.
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    	Li;	;	!	
               i	   ,    .    <	.«  . .   '                                                         .   .
            Where an EIS is required, scoping becomes a formal process that involves public participation and
            UTteragency coordination.
            Generally, a Notice of Intent for EIS preparation will contain an initial identification of potentially
            important issues associated with a proposed action. The NOI also will describe the proposed method
            for conducting the scoping process and will identify the office or person responsible for matters
            related to scoping. ,       '
            EIS preparation also involves holding one or more scoping meetings, where affected Federal, State,
            and local agencies, affected Tribes, and other interested persons are invited to participate in the
            identification of key issues.  Participants help draw attention to any other actions or previous
            assessments that may bear on the proposed action. In addition, the scoping process may involve
            addressing procedural issues. For example, the review and consultation procedures for the process
            may be identified, a planning schedule may be developed, and page and time limits for the assessment
           may beset.
                     • i in II
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           5.2    IDENTIFY ALTERNATIVES.
               !    ,             i                             .      ,  1
           In accordance with NEPA, impact analysis requires a description of the proposed action as well as a
           description of all reasonable alternatives.  The identification of alternatives is an essential step hi the
           preparation of ETOs, EAs, and FJSs.  For EISs, alternatives should be described in great detail.
           	  I                 II                                     ' i                   '
           The	description of alternatives should include an identification of any alternatives that were considered
                              the planning process.  Any reasonable alternative should be considered by the
                     in order to provide EPA with more latitude in considering whether to issue the permit or
           not. The rationale for the elimination of any alternatives from further consideration should be
           provided.* Alternatives generally are rejected based on tedbnical, economic, environmental, or
           institutional considerations.  In the case of an EIS, the decision to dismiss an alternative must be
           supported by data sufficient to respond to a challenging question or comment.
               ,
    :£r^:=EE_Uj	NEPAjwoceduxes	recognize	three general categories of alternatives:  alternatives available to'
               l	aJteraadyKOHgidered	by the applicant; and "alternatives available to other agencies with
                                                                •H£:M
                                                                IIIIIIH^^^	HIIIH^^^        	!!!H
                                                         5-2
         September 1994

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 ELA Guidelines for Mining	                                        Impact Analysis

 5.2.1    'ALTERNATIVES AVAILABLE TO EPA

 Three types of alternatives are available to EPA in assessing the potential impacts of a proposed new
 source NPDES permitting action:

      •  Issue the NPDES permit

      •  Issue the NPDES permit with modifications to the proposal (including modifications that
          may not have, been considered by the Applicant)

      •   Deny the NPDES permit.

 The third option is generally referred to as the "no action alternative."  This alternative provides a
 baseline for comparing the impacts of other options.

 5.2.2    ALTERNATIVES CONSIDERED BY THE APPLICANT

 When new industrial faculties are planned, operators typically undertake feasibility and planning
 studies.  Companies typically investigate processing options, markets, siting alternatives, and a host of
 other technical, financial, and legal issues.  These planning studies can be helpful in the early
 identification of critical issues, including potential land use conflicts, proximity to protected natural
 resources or historic sites, or any indication of hazard potential (e.g., location of facilities in
 floodplains).

 The Applicant should explain the planning process to provide insight into the breadth and depth of
 alternatives considered and rejected or pursued for further study.  A well-documented explanation of
 the Applicant's analysis of alternatives is critically important to die impact assessment process.
 In particular, it is important  for the Applicant to explore and document a broad scope of alternatives
 that look at pollution prevention opportunities.

As part of an EID, the Applicant should provide a detailed description of the proposed action(s) as
well as a description of any alternatives that were considered, but rejected.  The Applicant should also
consider the "no action alternative," which would be not to apply for the NPDES permit.

EPA's NEPA procedures require that the Applicant provide: (1) "balanced" descriptions of each
alternative and (2) a discussion covering size and location of facilities, land requirements, operations
and management requirements, auxiliary structures such as pipelines or transmission lines, and
construction schedules.
                                             5-3                               September 1994

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            Impact Analysis
                                                                    EIA Guidelines for Mining
IIIIIIH
            The Applicant should explain the implications of each option with regard to the firm's goals and
            objectives.  The Applicant should consider the full range of options for meeting these goals and
            objectives, including options that do not involve a discharge subject to permit requirements.
 5.2.3    ALTERNATIVES AVAILABLE TO OTHER AGENCIES

 A third category of alternatives are those available when EPA is preparing an EIS or other
    In i    i   in  ,  i    	in           i     •         „  r                      	•	
 environmental document hi conjunction with another Federal or State agency. These additional
 alternatives would be based on other relevant regulatory authorities. For example, hi addition to a
 new source NPDES discharge, a proposed project might involve dredging or filling of a wetland.  In
 mis case, the U.S. Army Corps of Engineers would be responsible for issuing a permit under Section
    of the	CWA., Accordingly, the environmental analysis should account' for the' various alternatives
           available to the Corps of Engineers, which would include: granting the permit; granting the permit
           with modifications or conditions; or denying the permit.  The information to support issuance of a
           permit under Section 404 should be included in the EIS, including how impacts to aquatic resources
                                      compensated for.
were avoided, minimized, or compensa
           5.3    DESCRIBE THE AFFECTED ENVIRONMENT

           The affected environment section of any NEPA document should be no longer or more detailed than
           Deeded to understand potential environmental impacts. Background information on topics not directly
           related to expected effects should be summarized, consolidated, or referenced to focus attention on
           important issues.
          The scope and content of this section of an EID will be determined during an initial consultation
          between EPA and the Applicant.  Generally, the Applicant will be required to provide any relevant
          information that is readily available.  In establishing the scope of this section of an EID, EPA will
          	consider the size of the new source and the extent to which the Applicant, is	capable	of providing	
          information. Requests for data should be kept to a minimum consistent with requirements under
                	iL1	J	'	'    	'	;":"	"	!


          For	an EA, the description of the affected environment should focus on key issue areas, including the
"'	:	::	:	" following:
                    Current and projected land use within the project area and within the region
          i	si	i	•	  Current	and projected population and population density
                   Relevant land use regulations
                *  Leial and regional patterns of energy demand and supply
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                                                                                        September 1994

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 "EIA Guidelines for Mining	Impact Analysis

      •   Local ambient air quality conditions   •

      •   Local ambient noise levels

      •   Location of designated floodplains within the vicinity of the project

      •   Surface water and groundwater quality and .quantity

      •   Local biological communities and fish and wildlife habitats

      •   Critical habitats of any Federal- or State-listed threatened or endangered species

      •   Location of any properties listed in or eligible for listing in the National.Register of
          Historic Places

      •   Location of specially protected areas,  including parklands, wetlands, wild and scenic rivers,
          navigational areas, or prime agricultural lands.

in the case of an EIS, the description of the affected environment is more extensive and detailed. The
breadth of topics typically addressed within an EIS is discussed below.

5.3.1    THE PHYSICAL-CHEMICAL ENVIRONMENT

The physical-chemical environment comprises the air, water, and geological characteristics of sites
where the environmental impacts of alternatives will be evaluated. This section of an EIS should
provide sufficient information to determine whether impacts are likely to be significant.

53.1.1    Air Resources

Air resources are described by the physical dynamic behavior of the lower atmosphere and by
variations in the concentrations of various gases and suspended flatter.  Physical dynamic behavior is
described by parameters such as  the seasonal distribution of wind velocity and the frequency and
height of inversions.  Wind velocity and the frequency of occurrence of inversions are often
determined by specific local topographic features, particularly surrounding hills or mountains.  Air
quality is described by the variations hi the concentrations of pollutant gases hi the lower atmosphere.
Both are needed to determine the environmental impacts of facility stack emissions, the effects of
mobile sources on local ah* quality, and the likelihood that dust will be  of importance during
construction, operation, and after abandonment.

The description of meteorological regime(s> should include a generalized discussion of regional and
site-specific climate including:

      •  Diurnal and seasonal ground-level temperature
                                              5.5                              September 1994

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  "            Impact Analysis
EIA Guidelines for Mining
                       Wind characteristics at different heights and times (wind roses are particularly helpful and
                       Pr°Y^5 ^^? 5E??? Direction, ^K^ipy, and stability characteristics of the atmosphere)

                       Total monthly, seasonal, and annual precipitation, frequency of storms and their intensity,
                       including both average and extreme events
                                                                                             11           '    "  ' I  ' Ih
                                                                                             	,	    41   '.'

                   *   HeigBt* frequency, and persistence of inversions and atmospheric mixing characteristics

                   *   Description of pattern(s) evident for days of significant pollution episodes; evaporation.
            Information on ambient air quality is often required to predict the impacts during construction and the

            pollution concentrations can,be predicted for comparison with various Federal, State, and local
                        Depending on the scale of the analysis, data' should be presented for the relevant airshed,
                the, site itself, or both.  Also, the site's location relative to airy Class I areas (e.g., National Parks)
                     areas that are in nonattainment with any National Ambient Air Quality Standard should be
            Emission inventories and ambient air quality as reported by State and local air pollution control
            ^^f15 are ** data sources for an air basin or regional airshed level analysis.  At a minimum, .major
            sm**j°as*y S0laces snA %"" en^ssipns shou|4 be cjiaracterized, with diurnal variations in emissions by
           !™°?£	££'	«i ?eak, season for pollutants of concern.  P^jectionsjifjncreases	|n	emissions,	and	;	i
            long-term pollutant concentrations are also important at this level.  The comparison of expected trends
            with existing Federal, State, and local standards (including identification of Cjass I areas and the
            attainment status  of the area) becomes a major design parameter far gaseous emfcsion controjls.

           Site-level analyses are more detailed in their geographic scope, but  require similar  information.  One

                                                                of odors' dust»
                       iSfiSS	i22S2SS°,5	2?y becom& important in	detennjnjng local impacts. Air quality
                                 to determine me directions and ground level concentrations of pollutants of
                        4^ models require most of the information described in the previous paragraph along
                                                                emission	temperature, emission velocity, and
                                   . of the stack gases.
           IIIH^
           5.3.1.2    Water Resources

           Information on water resources to be hicluded in the affected environment chapter should cover:
           whether these waterbodies are jurisdictional waters of the United States, any special aquatic sites,
           descriptions of waterbody types (i.e., local streams, lakes, rivers, and estuaries), and descriptions of
           groundwater aquifers.  Descriptions of water body types, flows and dilutions, pollutant
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                                                           5-6                                September 1994
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.  'E1A Guidelines for Mining            •           .            •                  Impact Analysis

  concentrations, special aquatic sites, and habitat types near potential discharges are necessary to
  determine the changes hi the water environment that will occur with facility construction and
  operation. Descriptions of alluvial and bedrock aquifers are necessary to determine the potential for
  contamination of groundwaters from site activities.  Of key importance here is the depth to the water
  table, and the nature of overlying soils and geologic features.  Descriptions of groundwaters  should
  include the location of recharge areas, and, in areas of water shortage, then- present uses.

  Descriptions of surface waters should include seasonal  and historical maximum,  minimum, and mean
  flows for rivers and streams, and water levels or stages and seasonal patterns of thermal stratification.
  for lakes and impoundments.  The use of surface waters (diversions, returns; and reclamation) may
  also be important in certain locations where water resources are scarce. Information on ambient
 concentrations of pollutants, and other local sources, are also necessary to determine resulting
 concentrations of pollutants with new discharges.

 If imported water is to be used at the site for process water or other purposes, the source, quantity,
 and quality of the water should be described.  Any existing NPDES permits should be identified along
 with a description of wastewater flows and quality.

 If the site might be subject to flooding (is within the 100-year floodplain), the dates, levels, and peak
 discharges of previous floods should be reported along with the meteorological conditions mat created
 them. Projections  of future flood levels should also be  included for typical planning levels of SO- and .
 100-year floods..  These projections should include anticipated flood control projects such as levees
 and dams that will  be built.

 53.13    Soils and Geology

 The physical  structure of soils and their underlying geologic elements determine the extent to which
 soils will be affected by facility construction and operation. Useful parameters include permeability,
 erodability, water table depth, and depths to impervious layers.  The engineering properties and a
 detailed description of surface and subsurface soil materials and their distribution over a site provide
 most of the information necessary.

 Local  and regional  topographic features such as ridges, hills, mountains, and valleys provide
 information on watershed boundaries, and site topography (slope and elevation characteristics)
 provides information that is needed in determining the potential for erosion.

 Geological features are important when paleontological sites and other areas of scientific or
 educational value may be disturbed or overlain by facility structures.
                                               5.7                              September 1994

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                                        Ill Mill ill I
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             Impact Analysis
                                                                            EIA Guidelines for Mining

             In regions of the country that are seismically active, the description of the affected environment .
             should information necessary to assess potential risks.  Relevant information can include proximity to
             faults, the history of earthquakes in the area, locations of epicenters, magnitudes, and frequency of
             occurrence.                     •                      '
                                                                                                                          	ii
            5.3.2     BIOLOGICAL CONDITIONS                .                                  .
                             M  i n i              11                              i        .     11
                                        \
            Key elements of a description of biological conditions include the distribution of dominant species,
         •   identification and description of rare, threatened, or endangered species, and a characterization of
            ecological interrelationships.
St;ft3.i.I      >        .      ,  .    	i.     .' ,,,,	 -, ,   ":,(.   • •      	' ' '
            distribution of vegetation types within the project area. The presence in the area of rare, threatened,
            or endangered species and unique'giant assemblages are particularly important, especially if any are
            likely to occur at the site.  There are a variety of ways to describe vegetation, but the most useful is
            to divide the site flora into four or five "typical" assemblages and map their distribution and that of
                  ized scientific and educational areas.  For threatened, endangered, or rare species, however, it
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         .   is- necessary to map their occurrence separate

            In areas subject to forest fires, fire hazard should be described by describing the history of fires hi the
            area, projecting the severity of fire hazard hi the future, and describing existing fire control and
                f""-	•.! i  "   •	:	"	•       ••    •               H, •
            management actions.
           Aquatic and marine vegetation, particularly in the vicinity and downstream of proposed discharges,
           also should be characterized.  General .community characteristics, including dominant species and
                 sity, should be identified.
   diversi
                       Wildlife           '            .
                 N       """                                                 I
           The presence of wildlife at a site is largely dependent on the nature and distribution of vegetation.
                i    '        ' r   i  i                                                          i
           Particular emphasis should be placed on the presence of rare, threatened, or endangered species hi the
           general vicinity of the site, and she-specific discussions are mandatory when the site provides habitat
           that is used by rare, threatened, or endangered species. Under these circumstances, the relative
           abundance of all rare, threatened or endangered species and the dominant wildlife fauna should be
           surveyed on site and presented in the EIS.  Otherwise, a general description of the wildlife species
           within the area is sufficient.
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 EIA Guidelines for Mining _ _ _ _ __ _ Impact Analysis

 5.3.23    Ecological Interrelationships

 A characterization of the key interrelations and dynamics within an ecosystem provides a foundation
 for impact assessment.

 Although it is difficult to determine the extent to which plants and animals are interdependent at a
 given site* specific attention should be given to identifying the food sources of dominant or rare
 animal species, the factors that limit these food sources (including factors such as soil structure and
 moisture content, -soil surface temperature ranges, and specific soil micronutrients), and the ability of
 animal species to substitute food sources should current food sources be reduced hi abundance.
 Ecological interdependencies hi aquatic systems are also important, and aquatic communities change •
 dramatically with  large increases in nutrient or sediment discharges. While prediction of changes hi
 plant and animal populations is difficult under the best of circumstances,  significant changes (either
 positive or negative) cause concomitant changes hi both terrestrial and aquatic fauna.

: 533   SOCIOECONOMIC ENVIRONMENT

 The socioeconomic environment encompasses the interrelated areas of community services,
 transportation, employment, health and safety, and economic activity. The activities associated with
 the construction and operation of new source facilities must impact human resources (employment,
 population, and housing), institutional resources (services or facilities), and economic activity.  The
 information required to assess impacts are described below.

 533.1    Community Services
                                     . •                             v
 Community services such as water supply, sewerage and storm drainage, power supply, and
 education, medical, and fire and police services are almost always affected by major new projects.  It
 is important in an EA or EIS to describe the nature of existing public facilities and services within the
 general vicinity, the quality  of the service provided, and the ability of the existing public facilities and
 services to accommodate additional users. The most critical consideration is  the level of services that
 would be provided hi the anticipated peak year assuming no project were to be undertaken.
           and temporary household relocations create demands on the housing market. The number
 of nearby housing units, then* cost, vacancy rates, and owner-occupancy rate are all significant factors
 hi determining the suitability of the existing housing stock for occupancy by a temporary or
 permanent workforce. In addition, the present rate of growth within the housing sector can be
 compared with the anticipated growth hi housing supply and demand and the amount of land available
 for new housing to determine whether existing policies and attitudes toward growth are adequate to
 accommodate the additional residents.
                                              5.9                               September 1994

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i"!|''ln|       -     11"	 ,  '       	  ""t     '   '                       '    I.          ' !!!	, ''"'I     '   '
      .,      '!	,         ,.',   .   '            •      •	;	•            ,    '.
           Impact Analysis	          EIA Guidelines for Mining
           5.3.3.2    Transportation
                          l|                  	 	!	|	
           Transportation systems provide access to a facility for the import of raw materials, export of final
           products, and the movement of staff and service personnel.  All relevant forms of transport for the
           fecffity should be described. For all facilities, road-based transport is of potential significance, but
           railways, airways, pipelines, and navigable waterways may also be important for some facilities.
           Current traffic volumes, current traffic capacity, and an assessment of the adequacy of the systems for
          meeing peak demands during construction and operation should be presented.
           S333    Population

           Total population, rate of growth, general spcioecononnc composition, transient population, and the
           ^f or n*31 aafpre of *&e local population are parameters needed to assess the importance of the
           impafts °f PSJffJ"!1*0^ c&iPges on the local community.  Information on average household size,
           average age, age/sex distributions, ethnic composition, average household income, percent of
           households below poverty -level, ....... and ...... median ...... educational ....... level ....... ajlgjr ...... a ..... more ...... refined analysis of
       .   project-induced changes. Projections of demographic trends for the region and project area without "
          the project are also necessary to determine the relative impacts of the project in future years.
                     *      '                       ii        •      i    »  i         !      '
........... ' .................... i:" ......... "::" ..... n~S3~3A ........ ] ................. Employment [[[ "
                      H^^H^I  - ''l''"1'* iiiii'iiiiiiiiiiiiiiiiiiiii i""" i ....... iii'iiiiiiiiiiiiiiiii II 'i ......... SiSii! " i! "I ««^^^^^^^^^^^  "In !!!•!!! i 'iSiiiiSiii    .  1 1 ..... !'!'!!!'!!" "i ' ! ' j!"!!""ii!!i WT1I ....... i ..... i i ...... | ........... 1 I ..... .   ..................... In
                      » ...... S2S2JI.SE ...... fiS ..... iSSiSSJction ...... and ...... operation of any .new facility.  Construction is
          nonnS& 2E25! 2HS te 4 temporary workforce of construction workers, not by the permanent
          workforce  in the area near the site. Qn the other hand, facility operation usually relies on a
          pennanent workforce, and the source of personnel for this workforce may be local or from other
          parts of the country. In any case, increases in the number of personnel required to build or operate a
          ^7;?** ""P***** * accomPani«!1J>Z ...... 555?** ....... in employment in enterprises required'to
          support the imcfliry, indirect (secondary, non-basic) employment, as demands for goods  and services
          316 v****-  The direct and indirect employment generated by a project, in turn, generates
      ............................
        ^va^°ftoasefaolds.resultiiigrnpoin            and changes in the demographic
        characteristics of communities.
        To defzmme impacts of additional employment on the local enyironrnent, it is necessary to present
        information about the local labor base-where people work, what they do, their skills and education
       	Jgjji'!	fi—SSiSTO	—	SSffiESfiSSHE	.HE:	H*	gsaastiaia	alfee	unemployed    •
        ^"T011 m especially important if Sere is an expectation that a new facility will generate
        employment for them. Projections should also be included on anticipated trends in employment and

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 EIA Guidelines for Mining	                    Impact Analysis

 5.3.3.5    Health and Safety

 Description of the present health and safety environment should include statistics on industrial
 accidents in the local area; a discussion of-air, water, and radioactive emissions from existing and
 prior facilities and their effects on human health and the environment; and an analysis of present
 levels of noise and their impacts on people and wildlife. The identification of applicable regulatory
 standards provides a benchmark  against which the present and future health and safety environment,
 with and without the project, can be judged.

 5.3.3.6    Economic Activity

 Economic activity will always be affected by new facilities. Current economic activity should be
 described by characteristics of local businesses (number and types of businesses, annual revenues, and
 ownership patterns) and the availability of capital for future growth. To predict changes in the kinds
 of economic activity mat would occur with the project, it is necessary to describe the kinds of goods
 .and services that would be required by the project or associated workforce and determine whether
 they are provided locally or imported. Unique features of the business community such as high
 seasonally, high outflow of profit, declining trade, or downtown revitalization should also be
 included.

 5.3.4  '  LAND USE

 A description of land use should  identify the current use of land needed specifically for the facility,  its
 system components, its safe area, and its residuals; and land us& patterns in the nearby area that will
 be indirectly affected by the project.  Particular emphasis should be placed on land uses that pose
 potential conflicts for large-scale  industrial activity—residential areas, agricultural lands, woodlands,
 wetlands—and on the local or regional zoning laws that may limit the development of industry or
 commercial activities on which it relies.  Also of crucial importance is the anticipated (and/or
 required) use of the land once mining operations end. ,

5.3.5    AESTHETICS .

Aesthetics involve the general visual, audio, and tactile environment (imagine the sensory differences
among urban, industrial, agricultural, and forest environments). A description of the aesthetic
characteristics of the existing environment should include things that are seen, heard, and smelted in
and around the  site  and their emotional or psychological effect on people.  Descriptions (or pictures)
of views of the site, of unique features or features deemed of special value, and public use and
appreciation of the site provide information that must be available for the assessment of impacts.
                                              5-11                              September 1994

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       Impact Analysis
EIA Guidelines for Mining
                          ii-
       5.3.6    CULTURAL RESOURCES
          i                 ii           ,                                            i           •
       Cultural 'resources is a broad category that encompass resources of current, prehistoric and historic
       significance.  The location of a facility near significant historical and cultural sites can degrade their
       resource value or emotional impact.  The location of the following kinds of sites should be described
       in relation to the project site:
                           I                          i                      i       i   i    .
                                                                                (
            •   Archeological sites (where man-made artifacts or other remains dating from prehistoric
            .................... times are" found)                     '            ".                 •

            >   Paleontplogical sites (where bones, shells, and fossils of ancient plants or animals are found
                in soil or imbedded in rock formations)

            >   Historic sites (where significant events happened or where well-known people lived or
                worked)

                Sites of particular educational, religious, scientific, or cultural value.
     "'Of particular concern ^^1^ beicaoq»ly^. v^ §106 of the National Historic Reservation Act for
...................... • ....................... sites listed on, or eligible for listing on, the National Register.

 "l! ..................... ^ ............. 5.4    ANALYZE POTENTIAL 'IMPACTS
          !.•;     .. .  ."   • .....     ••        :     •           •          .      "•  ••     !:     '
      The major environmental issues associated with the mining industries were discussed hi the previous
     chapter. Although Chapter 4 presents guidance for the analysis of impacts that tend to be common to
     these industrial categories, it is important to recognize.that other types of impacts are bound to be
     assoc ated	with	specific proposed actions.  Thus, reviewers must ensure that all key- issues identified
     during the scoping process are fully analyzed.  The section below provides more specific guidance on
     the preparation of the "Environmental Consequences" section of an EIS.  It also serves as the focus
  "" of any administrative appeal or -legal challenge of the permit.
       	I	:;	;	;	;	;	;	:	;	:	:	;	'	:	:	'	:	":::;	:
     The "Environmental Consequences"  section of an EIS forms the scientific and analytical basis for the
          I t          i   ni i  i                    .                        i in i i     i •
     comparison of alternatives. Accordingly, it should contain discussions of beneficial and adverse
     impacts of each reasonable alternative and mitigation measure (40 CFR 1502.16 and 1508.8)
          I";,;;,   ,     -   ' "	" :  '  . ' "     ' , 	I    '                 ,                   •       '   '
     including clear, technical demonstrations of:
                                       	;;	;	,	|	J	
   —	:	;::; • *Z,;	2Iffip|	Sffscis	Sffil	IhSIE	significance—direct effects are caused by the proposed action and
              occur	at	the same time and place.

              Indirect effects and their significance—indirect effects are those caused by the action but are
                      !2S£	Si	iSSHS	JiSSSyiSii	Hi	liSSSSSz	but	are	reasonably foreseeable.  This also
                      	growth	effects	related	to	induced	changes in the pattern of land use, population
                      _   __^ ^__^ —^ rejj effects on air, water, and ecosystems.

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  EIA Guidelines for Mining  .		'                     Impact Analysis

       •   Possible conflicts between proposed actions and the objectives of Federal, regional, State,
           local and tribal land use plans, policies, and controls for the area concerned.

       •   Energy requirements and conservation potential.

       •   Natural or depletable resource requirements and conservation potential.

       •   Urban quality, historical and cultural resources, including reuse and conservation potential.

       •   Means to mitigate adverse environmental impacts not fully covered by the alternatives.

       •   Project compliance with water quality standards and the significance of the anticipated
           impact of the discharge (this is particularly important for new source permits).

       •   Project compliance with National Ambient Ah- Quality Standards and, if applicable,
           Prevention of Significant Deterioration increments.

 The potential impacts of each alternative are identified by a systematic disciplinary and
 interdisciplinary examination of the consequences of implementing each alternative.

 5.4.1   METHODS OF ANALYSIS                           '

 While information may be gathered from new source NPDES applications, HDs, and other sources,
 EPA is responsible for the scientific and professional integrity of any information used in EISs for
 which it is responsible.  The applicant's EID and other sources of data, therefore, must clearly
 explain all sources, references,  methodologies, and models used to analyze or predict results.  •
 Applicants should consider the uses and audiences for their data and EPA's affirmative responsibility
 in using them. EPA has the same responsibility in the use of data submitted by other agencies,
 private individuals, or groups.                       '      .

 Each impact has its own means of identification,  qualification, and quantification.  For example, air
 quality impacts are modeled using standard State or Federally approved programs.  These numerical
 models depend on standardized  parameters and site-specific data.  Stationary source emissions from
 plant operation as well as mobile emissions related to traffic circulation from induced employment or
 growth all  contribute to air quality impact quantification. The goal is to quantify impacts on air
 quality, water quality, employment, land use, and community services—categories that lend
 themselves to numerical calculations,  modeling, and projections.  Some environmental elements like
 aesthetics lend themselves to more qualitative or graphic analyses.

Biological impacts frequently are not readily quantifiable becaus: absolute abundance of individual
 species are difficult to determine.  Impacts may be described as acres of habitat lost or modified or to
qualitative  impact descriptions of population changes in major species or species groups.  The key in
the Environmental Consequences section is to clearly and succinctly lead a reader through each impact


                                             5-13                               September  1994

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         Impact Analysis
                                        EIA Guidelines for Mining
         identification, qualification and/or quantification. Detailed methodologies or extensive data can be
    !!_ ji|p»2£2S2	«X	SSSSfi	EiSLiXP?- ^ readav obtainable.  WUdltfe agencies can' be source of data
         W pSs section.  Materials from applicants must carefully follow this pattern to facilitate validation
         and incorporation in tfie EIS.                 •          .     	'.	
HiUlM	IIIIHIH                   	iiiii'ii	iiiiiii'PI 1,  "Pin	iiiiiiifiiiif'i  i ii N1  riw^^^^^^                	IB^^^^^^^^^^^^^^^^^^^^^^^      	i
                             '                '                   "    ~~	lr^.~^iHlU!llZ!l.™.!,^lirj	ZH^dt^l','.~'lilH.'Z
        5.4:2    DEIERRHNATION OF SIGNIFICANCE   	      '	:	'_	

        As djscussed in Chapter 2 of these guidelines, The term "significant effect" is pivotal under NEPA,
        for an EIS must be1 prepared  when a new source facility is likely to cause a significant impact. What
        is significant can be set by law,  regulation, policy, or practice of an agency;  the collective wisdom of
        a recognized group (e.g., industry or trade association^standards);  or the_ professional judgment of an
	expert or group of experts. CEQ (40 CER 1508.27) explains  significance in terms of .context and
        intensity of an action.  Context relates to scale—local,  regional. Slate, national, or global; intensity
        refers to the seventy of the impact. Primary impact areas include  affects on public health and safety,'
        and unique characteristics of the area (e.g., historical or cultural resources, parks, prime farm lands,
        wetlands, wild and scenic rivers, or ecologically critical areas). Other important factors include:

              '   Degree of controversy

                 Degree  of uncertain or unknown risks
                  Jkelihood	a precedent will be set
V
                                             ^S!? ie?ISc!?^y ^ individually not significant)
                        !2	which	sjtes	Ksted, or eKgible for listing, in the National Register'of Historic
                Places	may be affected
                Degree to which significant scientific, cultural, or historical resources are lost

                Degree to which threatened or endangered species or their critical habitat is affected

            *   The, iike#ho<|| of violations of Federal, State, regional or local environmental law or
                requirements or alternatively, likelihood that applicable standards applicable to the operation
                and various environmental media can be achieved.

      EPA's NEPA procedures require that the Agency consider short-term and long-term effects, direct
      and indirect effects, and beneficial and adverse effects.. Of particular concern are the following types
     »of impacts:            " •  '                     .'     '               •	     •
                The new source will induce or accelerate significant changes hi industrial, commercial,
                agricultural, or residential land use concentrations or distributions which have the potential
                                                                  1	
                                                    5-14

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                                                 September 1994
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 ELL Guidelines for Mining	      Impact Analysis

          for significant environmental effects.  Factors that should be considered in determining
          whether these changes are environmentally significant include but are not limited to:

              The nature and extent of the vacant land subject to increased development pressure as a
              result of the new source

              The increases in population or population density which may be induced and the
              ramifications of such changes

              The nature of the land use regulation in the affected areas and their potential effects on
              development and the environment

              The changes in the availability or demand for energy and the resulting environmental   •
              consequences.

      •   The new source will'directly, or through induced development, have significant adverse
          effects upon local ambient noise levels, floodplain, surface or. groundwater quality or
          quantity, fish, wildlife, and then: natural habitats.

      •   Any major part of the new source will have significant adverse effect on the habitat of
          threatened or  endangered species on the Department of the Interior's or a State's list of
          threatened and endangered species.

      •   The environmental  impacts of the issue of a new source NPDES permit will have significant
       -  direct and adverse effect on property listed in the National  Register of Historic Places.

      •   Any major part of the source will .have significant adverse  effects on park lands, wetlands,
          wild and scenic rivers, reservoirs, or other important bodies of water, navigation projects,
          or agricultural lands.

With the regulations hi mind, it is ultimately up to the EA and/or EIS preparer(s) to make judgments
on what constitutes a significant impact. The threshold of significance is different for each impact,
and those making the judgments need to explain the rationale for the thresholds chosen.  Clear
descriptions of the choice of the threshold of significance provides a  reviewer with a basis for
agreeing or disagreeing  with the determination of significance on based on specific assumptions,
criteria, or data. Sometimes the thresholds are numerical standards set by regulation. In other cases,
the thresholds may be set by agency practice (e.g., the U.S. Fish and Wildlife Service may consider
the potential loss of a single individual of ah endangered species as a significant impact), or the EPA
preparer's professional judgment that determines the rationale for the threshold.  The NPDES permit
applicant may suggest a threshold for each impact identified in the EID, but it is critical  to carefully
define how and why each particular threshold was chosen and applied.
                                             5.15                              September 1994

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!!i!!!!!!i! iiiil!!!!!!!!!!!!!1!' i!!!!!!!!!!!!!!!!!!!' "i!'!!!! "!!!!««!!!!«""!•!!!!!!!!!!!!!!!«'"" in!!!!!!!!!!!!1'!!"!'!' !!!!!!•!!!!!!!!!!!!!!!!!!!!!!!!!!!!•!!


              Impact Analysis
                                                                                  EIA Guidelines for Mining
                                                               t
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              5-4.3    COMPARISONS OF IMPACTS UNDER DIFFERING ALTERNATIVES
                      ' i,,''  ,*'i  ''•'•"•  '   /  •    ;.'     "'  •>'.    •'       '  > '.i,  i  ,    :!     ,    ,]."•..•! '!„  ' :'   ''  ..
             Alternatives can be compared in several different ways. All of the impacts associated with a single
             alternative may be examined together and summarized in a final list'of significant unavoidable
             impacts, or  the like impacts of all the alternatives can be determined and compared within a final
             summarized list of significant unavoidable impacts.  The choice of approach should be determined by
            me
               t &S preparers based on the approach that would.provide the most clear, concise evaluation for
             decision makers and reviewers. The summary information on possible impacts and mitigation
             measures is usually prepared in tabular form and included in the executive summary.  Examples of
             ft)rpats that can be used are found in standard_environmental assessment technology texts, agency
             maiiibate,  EAs, EISs, and similar documents.

            5.4.4    SUMMARY DISCUSSIONS
IIIIIIH    ..... IIIL
            CECJ and EPA NEPA guidelines describe the expected general ...... .contents, ....... of; the ...... section ...... called [[[
            "Environmental Consequences." In addition to identifying, quantifying, and comparing the impacts
            of each alternative, 40 CER 1502.16 specifies that discussions will include "..any adverse
            P^ffiiSM, Exacts which cannot be avoided should the proposal be, implemented, the relationship
            between- short-term uses of man's environment and the maintenance and enhancement of long-term
            productivity, and any irreversible or irretrievable commitments of resources which would be involved
            in .the proposal should it be implemented."

            Over the last 20 years, these three topics have been included as a separate chapters) in draft EISs
            along with chapters called cumulative impacts, adverse effects which cannot be avoided, or residual
            impacts and mitigation. No matter what format is used with these topics, they often receive only
            cursory treatment.  Such a practice is unfortunate because these long-term,  larger scale issues are
           those that affect overall environmental quality and amenities. The important point is not the location
           of these topics in the document, but the need to present data, and analytical procedures used to qualify
                       these concerns.
  nil i in i iiiiiiiini i iii
           A section called cumulative impacts can be addressed in several ways.  Some EISs consider
           cumulative impact sections to be summaries of all residual impacts for each alternative. They may
           also inciude'any synergistic effects among impacts.  A second, and more helpful, approach to
           cumulative impacts reflects a broad view of environmental quality and suggests how impacts of the
           proposed project or alternatives contribute to the overall environmental  quality of the locale, in the
           immediate future and over a longer time.  In this approach, the impacts of the new source project are
           considered m relation to the impacts associated with projects approved,  but not constructed; projects
        ,, jfglP*, considered for approval; or planned projects.  This "accumulating" impacts approach to
          cumulative impacts is particularly instructive when no single project is a major cause of a problem,'
          but contributes incrementally to a growing problem
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                                                        5-16

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EIA Guidelines for Mining
                                                                             Impact
All of these summary topics focus on broad views and long time lines in a attempt to put project
impacts in perspective. . The data requests from EPA to applicants must specify the environmental
setting and consequences data needed to qualify and quantify the potential impacts and put each
potential impact in perspective in terms of local, regional and perhaps State or national environmental
quality.                                   •

5.5    DETERMINE MITIGATING MEASURES

Initial efforts to meet requirements under NEPA emphasized the identification of mitigation measures
for all potential impacts conceivably associated with a project or its alternatives. Current practices
emphasize avoiding and minimising potential impacts before a NEPA document is prepared. This is
accomplished by refining the proposed project and alternatives during siting, feasibility, and design
processes.  The goal is to propose project alternatives with as few significant impacts as possible.

CEQ NEPA regulations define mitigation (40 CFR 1508.20) to include:

      •  Avoiding the impact altogether by not taking a certain action or parts of an action

     *  Minimizing impacts by limiting the degree or magnitude of the action and its
         implementation
      •  Rectifying the impact by repairing, rehabilitating, or restoring the affected environment

      •  Reducing or eliminating the impact over time by preservation and maintenance operations
         during the life of the action           v  •     '

      •  Compensating for the impact by replacing or providing substitute resources or
         environments.

This listing of mitigation measures has been interpreted as a hierarchy with "avoiding impacts"  as the
best mitigation and "compensating" for a loss as the least desirable (but preferable to loss without
compensation). This hierarchy reinforces the present approach of trying to avoid or minimize
potential impacts during project siting and design. The goal is to have the most environmentally
sound project and alternatives to carry into  the impact assessment process of NEPA.

Even with the best project siting and design, there will be environmental impacts associated with each
of the alternatives. For the impacts, especially for the impacts judged to be significant impacts,
mitigation measures need to be suggested.

The first source of possible mitigation measures should be those offered hi an applicant's EID.  Each
mitigation measure should be described in enough detail so that its environmental consequences can
be evaluated and any residual impacts clearly identified.
                                             5_17                             September 1994

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       Impact Analysis
EIA Guidelines for Mining
                             ive typically reflects choices among tradeoffs. The tradeoffs can include
                          , pollution control technologies, costs, or other features.  Typically the tradeoffs
        Sj"|ii5fplex	for	new	source	facilities	with	dfcsimilar	beneficial	and	detrimental	impacts among the
              3S|:	il|	ill	Il&ays	shojii	Ascribe	the process that led lp, and the rationale far,, .the,
      selection of the preferred alternative.  The analysis should be deemed complete if:

                Tie alternatives brought forward for analysis are all reasonable

=;=:£=:   •   All possible refinements and modifications for  environmental protection have been


^I="::=;   •   Any	residual	impacts and consequences of mitigating those impacts have been evaluated.

      II!~                                                                                             	•"

           of the many laws, regulations, executive orders, and policies identified hi Chapter 6 should be
         •jjsssssaa	a*,	the	Consultation	and	Coordination section of an EIS.  The applicant should provide a
         ji9' ^^£^{2yj{fe£	and	gptipjis	uj3er	easfe	o£|^jriiti|tiiess	lie	appicar^nmded
      environmental setting and environmental consequences materials should include sufficient data on the
         _          _      	liiiiBjj	i	i	i	!,	i	_	,	,	
      envtfotim&tt:	issues	raised	by these laws, regulations, and orders to identify and analyze the potential
      Impacts.          	   •                                 '                  '    ".	'. '.

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                                                       5-18                                  September 1994
                             I	gj	;	,	           	'	•	i	           .

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 E1A Guidelines for Mining                                              Statutory Framework

                            6.  STATUTORY FRAMEWORK


 Mining operations are subject to a complex web of Federal, State, and local requirements.  Many of
 these require permits before the mining operations commence, while many simply require
 consultations, mandate the submission of various reports, and/or establish specific prohibitions or
 performance-based standards. • Among the Federal statutes that are potentially applicable are those
 shown in Exhibit 6-1.  Also shown are the agency with primary responsibility for implementing or
 administering the statute and the types of requirements that are imposed on those subject to various
 statutory provisions.

 The following sections describe the purposes and broad goals of thes,e statutes.  The discussion for
 each statute also provides an overview of the requirements and programs that are implemented by the
 respective implementing agencies.

 6.1    CLEAN WATER ACT

 The objective of the Clean Water Act is to "restore and maintain the chemical, physical, and
 biological integrity of the Nation's waters" (§101(a)). This is to be  accomplished through the control
 of both point and nonpoint sources of pollution (§101(a)(7».  A number of interrelated provisions of
 the Act* establish the structure by which the goals of the Act are to be achieved.  Within this overall
 structure, a variety of Federal and State programs are implemented to meet the Act's requirements.

 Under §303, States are responsible for establishing water quality standards and criteria for waters
under their jurisdictions:  these are the beneficial uses that various waters are to support and the
 numeric (and narrative) criteria that must be achieved to allow these uses to be met.  Water quality
standards and criteria serve as a basis both for identifying waters that do  not meet their designated
.uses and for developing effluent limits in permitted discharges. EPA also establishes nonbinding
numeric water quality criteria as guidance; when States fail to adopt sufficient water quality standards,
EPA may do so.                                                                              .

Under §402 of the Act, all point source discharges (see below) of pollutants to navigable waters of the
United States must be permitted under the National Pollutant Discharge Elimination System. (NPDES).
Effluent limits in NPDES permits may be technology- or water quality-based.  For various categories
 of industries, EPA establishes National technology-based effluent limitation guidelines pursuant to
 §§301, 306, and 307.

 The term "navigable wcters" or "waters of the U.S." includes all waters within the territorial seas
 (i.e., within the three-mile contiguous zone around the United States).  Waters of the United States
 need not be navigable in fact (see U.S. v. Ashland Oil, 504 F2d 1317 (6th Cir. 1974)), and may be
                                             6-1                              September 1994

-------
	!	Statutory Framework
                                                                            EIA Guidelines for Mining
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Guidelines for Mining
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          Statutory Framework
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                                     6-5
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      Statutory Framework
EIA Guidelines for Mining
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        September 1994


-------
     Guidelines for Mining                             	    Statutory Framework
                    - ..   Point Sources Under fire dean Water Act

  The term "point source" means any discernible, confined, and discrete conveyances-including
  but not limited to any pnie, ditch, channel, tunnel* conduit, well, discrete fissure, container,
  rolling stock, concentrated animal feeding operation, orvessei or other floating craft from which
  pollutants are or may be discharged" fCWA §502(14)}. For purposes of the [CWA], the term
  "point source" includes a landfill leachate collection system.  1987 Water Quality Act, PL 100-
  4, §507. The definition has been codified at 40 CFR 122,2.         "         - A
                    •                                 f-   J- o
  M the preamble for a. storm water rulemaldng {55-FR 47997; November 19,199Q),"EPA cited
  court decisions mat bear on the definition (Sierra Club v. Abston Construction Cony any, 620
  F.2d (5flj dr. 1980)):  *. » , Nothing in me [Clean Waterl Act relieves [dischargers] from
  liability simpfy-because operators did. not construct mose conveyances, so long as they are
  reasonably likely to be the means by which pollutants are ultimately deposited into a navigable
  body of water. Conveyance of pollution formed either as a result of natural erosion or by
  material means, and which constitute a component of a»» - drainage system, may fit the
  statutory definMon and thereby subject the operators to liability under the Act." Overall* EPA
  concluded that it intended to *.. ». embrace the broadest possible definition of point source
  consistent with me legislative intent of the CWA and court interpretations to include any
  Identifiable conveyance from which pollutants might enter the waters of the United States.8
 - Further, EPA noted that facilities themselves had the burden of determining whether an
  application should  be submitted lor a point source (and, by implication, of determining whether
  a discharge was from a point source) and advised facilities to submit an application or consult
  with permitting authorities in cases of uncertainty. It should be noted mat Federal courts have
  spoken to the issue of point sources at mine sites? for example, in Kennecott Copper Corp. v.
  EPA* 612 F.2d 1232 (1O Ofc. 1979), the court was asked to rule on whether certain discharges
  were subject to 40  CFR Part 440. One of the court's conclusions was that whether certain of
  Kennecott's  facilities were point sources was a determination *to,be made In the lost instance hi
  the context of a permit proceeding."
intermittent or seasonal.  In at least one case, a discharge which was traced into and through
groundwater was considered a discharge to waters of the United States (see Quivera Mining Co. v.
U.S. EPA, 15 ELR 20530 (10th Or. 1985)).

EPA's NPDES regulations [40 CFR 122.21(1)] require prospective dischargers (in States wirnout an
approved NPDES program) to submit information to the EPA Region, prior to beginning on-site
construction, that will allow a determination by EPA of whether the facility is a new source. The
criteria for this determination are in 40 CFR 122.29.  The .Region must then issue a public notice of
the determination. If the facility is determined to be a new source, the applicant must comply with
the environmental review requirements of 40 CFR Part 6 Subpart F.  In preparing a draft new source
NPDES permit, the administrative record on which the draft permit is based must include the
environmental information document prepared by the applicant, the environmental assessment (and, if
applicable, the FNSI) prepared by EPA, and the environmental impact statement (EIS) or supplement,
                                                                             September 1994

-------
                                                                                      iiiliivlliipiillilliipililiiiiillliiiiliiiiiiliiiiiiil'ijlijii;!1',!
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                                        124:,?(b)(6M.^	'fa	addition, public 'notice for a'draft''new source. NPDES
                     or	which	an	EIS	must	be prepared cannot take place-until the draft EIS is issued [40 CFR •
              Parj 124.10(b)].
                                           ' •    	                      •
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             EPA has	established National technology-based effluent limitation guidelines for coal mining and
             preparation plants (40 CFR Part 434) ami ore mining and dressing (40 CFR Part 440).  National
             effluent limits	are based on three levels of technologies.  First, Best Practicable Control Technology
             Qirrendy Available (BPT) limits are based on the best existing performance (^|
             plants of various sizes, ages, and unit processes hi the industry.  Limits based on the Best Available
             Technology Economically Achievable (BAT) control toxic pollutants (i.e., 126 chemical substances
             identified by Congress) and nonconventional pollutants (any pollutant other than toxic and
             conventional, POD, TSS, oil and'grease, fecal	col!fbrm£	indpH]	poUutiEDte)!	§AT~llmits	generally	
             represent the best existing performance hi the industry. .Finally, new source performance standards
      III"™	"are based on the Best Available Demonstrated Technology (BADT), since new plants can install the
             J_M  —^ ^_^ egjcjenl production processes and'wastewater treatment technologies.  Exhibits 6-2
              «  ||              '      H"   ij'.. ' I '!• .  », T,,'l|  , "I ,    ••!'•!„ •  ' f,!   	„  ,,  ,!   •  ill'li, !•„ '• '">i,  , j,  , , , ,'"	•  ,
             through 6-4 present the new source performance standards for coal raining and preparation plants and
             ore mining and dressing facilities.

             In general, standards have been established for "mine drainage" and mill/preparation plant discharges.
             For coal mining, there also are standards for post-mining areas (i.e.,  reclamation areas prior to bond
             release).  For coal mining, mine drainage generally includes all point source discharges other than
             those from haul and access roads, rail lines, conveyor areas, equipment storage and maintenance
            yards, and coal handling buildings and structures (discharges/runoff from these areas  are subject to
            storm water permitting, as described below). For metal .mining, the discharges to which mine
            drainage limitations apply have proven somewhat more difficult to delineate; Exhibit 6-5 provides
            examples of point source discharges that are subject to mine drainage limits  (and examples of those
            that are subject to storm water permitting).
            The National effluent limitations consist of marmnim concentrations of individual pollutants that
            be present in specific discharges, as well as various conditions and exemptions; in some cases, the
            effluent limitation allows no discharge.  Typically, only a limited number of the pollutants that are
            likely or known to be present are limited in the National standards, since the technologies on which
            the limits are based prove effective in treating/removing other pollutants as well. Permit writers must
            use Best Professional Judgment to develop technology-based limits for any other pollutants of
            concern, and discharges, for which there are no National effluent limitations. In addition, when
            technology-based effluent limits will not ensure compliance with applicable water quality standards for
ill i iiii         .   i   . .          i   	.
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Guidelines for Mining
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                                           6-12
                                                        September 1994
                    	iini

-------
       Guidelines for Mining
                              Statutory Framework
           Exhibit 6-5.  Examples, of Discharges From Ore Mining and Dressing Facilities
                 That Are Subject to 40 CFR Part 440 or to Storm Water Permitting
        40 CFR Fart 440 effluent limitation: guidelines,
:'' i:--::":;.: i':'':Snbjert:;td- storm-water permitting
  - : t;:  fact subject to40 CFRPart 440) :•-.
     Mane drainage Snots
     Land application area '   .
     Crusher area ' '
     Spent ore piles ', surge piles, ore stockpiles, waste
        rock/overburden piles
     Pumped and unpumped drainage and mine water from
        pits/underground mines
     Seeps/French drams'   .            .
     Onsite haul roads, if constructed of waste rock or
        spent ore or if waste water subject to mine drainage
        limns is used for dust control
     Tailings dams/dikes when constructed of waste
        rock/tailings '
     Unreclaimed disturbed areas
     Mill discharges limits (including zero
     discharge limits)
     Land application area'
     Crusher area'            •       •
     Spent ore piles ', surge piles, waste rock/overburden
       piles
     Seeps/French drains '
     Tailings impoundment/pile
     Heap leach runoff/seepage             •  -
     Pregnant, barren, overflow, and polishing ponds
     Product storage areas  (e.g., concentrate pile)
 Topsoil piles
 Haul roads not on active mining area
 Onsite haul roads not constructed of waste rock or
   spent ore (unless wastewater subject to mine
   -drainage limits is used for dust control)
 Tailings dams/dikes when not constructed of waste
   rock/tailings '
 Concentration/mill building/site (if discharge is storm
   water only, with no contact with piles)
 Reclaimed areas released from reclamation bonds prior
   to 12/17/90
 Partially/inadequately reclaimed areas or areas not
   released from reclamation bond
 Most ancillary areas (e.g., chemical and explosives
   storage, power plant, equipment/truck maintenance
   and wash areas, etc.)
    NOTE:
    1  Point source discharges from these areas .are subject to 40 CFR Pan 440 effluent limitation guidelines for (a)
       mills if process fluids are present or (b) mine drainage if process Quids are not
Section §402(p)(2)(B) (added by the Water Quality Act of 1987) required that point source discharges
of storm water associated with industrial activity be permitted by October 1,  1992. Pursuant to this
requirement, .EPA's storm water program requires mat all point 'source discharges of storm water
associated with industrial activity, including storm water discharges from mining activity, be
permitted under the NPDES program. Storm water is defined at 40 CFR 122.26(b)(13) as "storm
water runoff, snow melt runoff, and surface runoff and drainage." Storm -water associated with
industrial activity is defined at §122.26(b)(14) as "the discharge from any conveyance which is used
for collecting and conveying storm water and which is directly related to manufacturing, processing,
or raw materials  storage areas at an industrial plant.  . . ."  It also includes discharges from "areas
                                                  6-13
                                  September 1994

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                       Framework
                                                                     Jljj	;	'	'	'	,	, 11 _,,!	.Jill	1	,	,	

                                                                        EIA Guidelines for Mining

               L           	:!     '                '        '   ,             f,        ;
             where industrial activity has taken place in the past and significant materials remain and are exposed
             ..              L  " .I      '       .'                -          	         .              .    '	•
             to storm water/
             Certain storm water discharges from mine sites, whether active or inactive, are not subject to NPDES
[[[ ! .................................................. permitting:  storm wafer, that ...... is ..... not ...... contaminated ...... by contact with or that has 'not come into .contact
^•w»»:i ...... with any overburden, raw material, intermediate products, finished products, byproducts, or waste
        | .................................... products located on the site of the ..... operation -is 'not subject to
          ' ....... Act.  Also, inactive sites where there is no identifiable owner/operator are not subject to permitting
SS-HBHHf ffiSoer ..... the ..... ^orm ..... ^ater rule (however, it is not clear that any sites are actually excluded by virtue of
                          ""  . ........ ,ll     I .                                             .   i    ' '
              .    „   ,        .  ,|l     I .                                              .   |i    '
            this, since there is presumably an owner of all 'lands on which sites may be located).  Finally, sites on
            Federal lands where claims have been established under the Mining Law of 1872 and where only
             ,  |! i       .  ', ..... IB "IS    • • ' ,'      -,i   !'  ...... ;  •'    ' ' ,.    '  ~                ... !    • ,•    ,'.  , J
            nominal claim-holding activities are being undertaken are not subject to permitting. However, it is
..................... 1 ..... ! .......... ::" ............... ;:™ ................................ " ^^^tjE^^pTQgR^wiIl address cjajn^ ....... wn^ ...... ^ ^ me case ^ ...... ^^ ...... mere ...... fe ...... a ...... discharge of .......
............. ' [[[ j«! ....... : .............................................. J! .............. ! ..... : ......................... i ........... ;i ........... • .................... s:?- ............... : ....... : ......................................... • ............... : .................................... • ...................... ; ......................... •: ........................... : .................................... [[[ : [[[ : [[[ • ...... ; ............................................. r ............... .................... i! ........... :s ........ ..................... ......... : .............................. » .......... ' .............. i .................. "
            contaminated storm water from mines  abandoned by a previous claimant.  Finally, NPDES permits
            are  not required for discharges of contaminated storm water from coal mines that have been released
                             btfi ....... 85 ..... iSffl ...... wttiln ..... sa ......         ..... oMLftm ...... ?pplicable
                                           or after December 17, 1990. ......
                                                                                    ill 1 1 1 iiiinnn ill 1 ill n i in 1 1
[[[         i ..................... nii«      ......
IIIIIIH^
[[[       I              ,                        .
            There ...... are ...... no ...... New ..... Source Performance Standards for storm water discharges, so the issuance of an
            Ni?DES permit for storm water discharges (or the coverage by an existing permit of a new or
            previously iinpermitted discharge) would not trigger NEPA.                !
           Section 404 of the Clean Water Act addresses the placement of dredged or fill material into waters of
           Itie	fj.S:	and	has	become	die principal' tool in the preservation of wetland ecosystems.  "Jurisdictional'
           wetlands" are those subject to regulation under Section 404. Jurisdictional wetlands are those that
       |Blgg|uijitai£	aufijrig	for	Section 404 'is divided between'the Arary Corps- of'Engineers" (Corps)" and
       	  EP4-  Section 404(a) establishes the requirement for the Corps to issue permits for discharges of
           dredged or till materials into waters of the United States at specific disposal sites.  Disposal sites are
           to bj:; specified for each permit using the §4O4(bXl) guidelmes; the guidelines were established by
           EPA in conjunction with the Corps.  Further, §404(c) gives EPA the authority to veto any of the
           permits issued by the Corps under §404.  In practice, EPA rarely exercises its veto power as it
           typically reviews and provides comments on §404 permits prior to their issuance, and any disputes are
           resolved then.
           Section 404(e) establishes that the Corps may issue general permits on a State, regional, or National
          , bgis,	foj	jglfS0™8 °f activities that the Secretary deems similar in nature, cause only

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 EIA Guidelines for M"»"g	Statutory Framework

 comment; the pennies must be based on the §404(b)(l) guidelines and establish conditions that apply
 to the authorized activity. Exceptions to §404 requirements are established in §404(f) and
 conditionally include the construction of temporary roads for moving mining equipment.

 The process of issuing a §404 permit begins with a permit application. The application typically
 contains information describing the project and the project area; wetlands to be disturbed and the
 extent; and, mitigation plans. Upon receipt of the application, the Corps issues a public notice
 describing the proposed activity and establishing a deadline for public comment.  Although a public
 hearing is not normally held,  one may be scheduled at the request of concerned citizens. Following
 the comment period (typically 30 days), the Corps evaluates the application based on requirements of
 the Clean Water Act. In the final stages, the Corps prepares an environmental assessment and issues
 a statement of finding. A permit is then issued or denied based on the finding.  It is at this time that
 EPA may exercise its veto authority.

 Enforcement authority is divided between the two agencies; the Corps provides enforcement action for
 operations discharging'in violation of an approved permit while EPA has authority over any operation
 discharging dredged or fill materials without a permit.  Within EPA, the Office of Wetlands
 Protection addresses wetland issues through two divisions.  The Regulatory Activities Division
 develops policy and regulations, and administers the statutory requirements including appeals and
 determinations.  The Wetlands Strategies and State Programs Division works to expand protection
 and further scientific knowledge of these ecosystem types through coordination efforts with other
 Federal and State agencies (Want 1990).

6.2    CLEAN AIR ACT

The Clean Air Act (CAA) (42 U.S.C. §§7401-7626) requires EPA to develop ambient air quality
standards as well as standards for hazardous air pollutants.  The Act also imposes strict performance
standards applicable to new or modified sources of air pollution, a stringent approval process for new
 sources of pollution in both attainment and non-attainment areas, and emission controls on motor
 vehicles.

Under §109, EPA has established national primary and secondary  ambient air quality standards for six
 "criteria" pollutants. These are known as the National Ambient Air Quality Standards (NAAQSs).
 The NAAQSs set maximum concentrations hi ambient air for lead, nitrogen oxides, sulfur dioxide,
 carbon monoxide, suspended particulate matter of less than  10 microns in diameter, and ozone.
 States and local authorities have the responsibility for bringing their regions into compliance with
 NAAQSs or more strict standards they may adopt.  This is accomplished through the development
 and implementation of State Implementation Plans  (SIPs), which are EPA-approved .plans that set
 forth the pollution control requirements applicable to the various sources addressed by each SIP.
                                             6-15                  .           September 1994

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                                     ^

 Statutory Framework
                                                                       EIA Guidelines for Mining
|!l'l ..... tinder §111, EPA has promulgated New ...... Source ..... Performance ..... Standards ..... (NSPSs) applicable to
;=:=  metallic mineral-ittocessing plants (40 CFR Part ,60, SubDart ffi- ^,'lSSSSSS, ,£!§?! ,E

              	of^quipment	fhtt produces	metallic	mineral	concentrates	from	ore;	metallic	mineral,	
              commences with the mining of the ore." However, all underground processing facilities
       exempt from the NSPSs.  Also, NSPS particulate emission concentration standards only apply to
         emissions. NSPSs require operations to contain stack-emitted particulate matter in excess of
     |.Q5 grams per dry standard cubic meter (dscm).  In addition, stack emissions must not exhibit
     i^mti        i p     |                                   HI   ,            „  |
                                            .           ,
 i^™ "   ,     'P     i                                    HI    •            in
greater man 7 percent opacity, unless the stack emissions are discharged from an affected facility
ging a wet scrubbing emission control device.  However, on or after 60 days following the
achievement of the maTinum production rate (but no later than 180 days after initial startup),
operations must limit all process fugitive emissions (meaning fugitive dust created during  operation
   j^i^HM^J^S!!^ ..... m ..... iSfSi ..... S ....... «ffE5t,,,,?pacity'      '              '
 ,; ..........
                                                       ;           '" i ,       i  ,        .
   In, addition to the NSPSs, Prevention of Significant Deterioration (PSD) provisions are intended to
   111 lnh| I' If l|ll|lllllllllllllllllllllll I lllilllllllllllllllllllllllllllill llllllllllllll||l|ll III i II1 llllllllllllllllllllll|l 111 Illlllllllllllllllllllllllllllllll Illlllllllllllllllllllllllllllllllllllllllllll 111 11111111111111 111 1111111 llnii| i iiiiiiiiiiiiini iiiiiiiiiiiiiiiiiiiiiiiiiiiiiini i •• iiiiiiiiiiiiiiiiiiini 11 minim iiiiiiiiiiiiiiiiiiiiini iiiiini iiiiiiiini i iiiiini iiiiini linn iiiiiiiiiiiiiiini iiiinpiiiiiiiiiiiini i iiiiiiini iiiiiiiiiinniiiii    n   i i        i i     *
   ensure that NAAQS are not exceeded in those areas that are in attainment for NAAQSs.  Under this
   program, new sources  are subject to extensive study requirements if they will emit (after controls are
   applied)	specified quantities of certain pollutants.
   State programs to meet orexceed Federal NAAQSs are generally maintained through permit programs
   that limit' the release of airborne pollutants from industrial and land-disturbing activities. Fugitive
 'IffcjSScions from mining activities may be regulated through these permit programs (usually by
   requiring dust suppression management activities).
     .                                                          ii   n
  As indicated above, only six criteria pollutants are currently regulated by NAAQSs.  Several other
Ii:Jll^SfS	££,	,332^2!	,S2!S	N.2S22?!,	.SSSSiSS,	SSJfeSfe!0!	SSSSSflpS	^Pollutants (NESHAPs)
  NESHAPs address health concerns that are considered too localized to be inchidol under the scope of
  NAAQSs.  Prior to the passage of me Clean Air Amendments of 1990, the EPA had promulgated
  NESHAPs for seven pollutants: arsenic, asbestos, benzene, beryllium, mercury, vinyl chloride, and
"!!	fadionudides (40 CFR Part 61).
 BJjfft	2S	—	,-S«&£&SS3SS&	S£l2aS	S&SSlSPy revised the existing statutory provisions of the
 i^CAA;	Tte	Amendinents	require that|	States	develop air emission permit programs for major sources
 3S5S,2S	2HIJ2S	S—21	2S!	,S2?2SaPy e^P30? *B au- toxics (i.e:, NESHAPs) program to '
 '"IS^SS	i§9	specific compounds. Under the Amendments, Cpngess requked ^EPA to .establish
  stringent, tedinplogy-based standards for a variety of hazardous air pollutants, including cyanide
  compounds.  In. November of 1993, EPA published a list of source categories and a schedule for
                 	fortfae	selected	sources. Among	the	mining-related industry groups that have been
            5 sojirces of hazardous air pollutants are the ferrous and non-ferrous metals processing
          ;, and the minerals products processing industry (58 FR 63952; 12/3/93J.  Under the
                                           6-16
                                                                               September 1994


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 ETA. Guidelines for Mining	.    	             Statutory Framework

 amended air toxics program, if a source emits more than 10 tons per year of a single hazardous air
 pollutant or more than 25 tons per year of a combination of hazardous air pollutants, the source is
 considered a "major source."  Major sources are required to use the Maximum Available Control
 Technology (MACT) to control the release of the pollutants (CAA §112). The CAA Amendments
 also intensify the requirements applicable to nonattainment areas.

 63    RESOURCE CONSERVATION AND RECOVERY ACT

 The Solid Waste'Disposal Act was amended in 1976 with the passage of the Resource Conservation
 and Recovery Act (RCRA)(42 U.S.C. §§6901-6992k). Under Subtitle C of RCRA, EPA has
 established requirements for managing hazardous wastes from their generation through their storage,
 transportation, treatment, and ultimate disposal. Hazardous wastes include specific wastes that are
 listed as such under 40 CFR §261  Subpart D as well as other wastes that exhibit one or more EPA-
 defined "characteristics," including reactivity, corrosivity, and toxicity.  Other solid wastes (which
 can be solid, liquid, or gaseous) that are not hazardous wastes are subject to Subtitle D, under which
 EPA establishes criteria for State management programs, approves State programs, and can provide
 funding for State implementation.  EPA has promulgated specific criteria for municipal solid wastes
 and more general criteria for all nonhazardous solid wastes.

 The scope of RCRA as it applies to mining waste was amended in 1980 when Congress passed the
 Bevill Amendment,  RCRA §3001(b)(3)(A). The Bevill Amendment states that "solid waste from the
 extraction, beneficiation, and processing of ores and minerals" is excluded from the definition  of
 hazardous waste under Subtitle C of RCRA (40 CFR §261.4(b)(7)). The exemption was conditional
 upon EPA's completion of studies required by RCRA Section 8002(f) and (p) on the environmental
 and health consequences of the disposal and use of these wastes.  EPA then conducted separate studies
 of extraction and beneficiation wastes (roughly, mining and milling wastes) and processing wastes
 (smelting and refining wastes).  EPA submitted the results of die first study in the 1985 Report to
 Congress: Wastes from the Extraction and Beneficiation of Metallic Ores, Phosphate Rock, Asbestos,
 Overburden From Uranium Mining, and Oil Shale (EPA, 1985).  In July 1986, EPA made a
 regulatory determination that regulation of extraction and beneficiation wastes as hazardous wastes
 under Subtitle C was not warranted (51 FR 24496; July 3, 1986). EPA found that a wide variety of
 existing Federal and State programs already addressed many of the risks posed by extraction and .
 beneficiation wastes. To address gaps in existing programs, EPA indicated that these wastes should
be controlled under a Subtitle D program specific to mining wastes.

 EPA reported its findings on mineral processing wastes from the studies required by the Bevill
 Amendment in the 1990 Report to Congress: Special Wastes From Mineral Processing (EPA, 1990).
 This report covered 20 specific mineral processing wastes. In June 1991, EPA issued a regulatory
determination (56 FR 27300; June 13, 1990) stating that regulation of these 20 mineral processing
wastes as hazardous  wastes under RCRA Subtitle C is inappropriate or infeasible.  Eighteen of the


                                           6-17                             September 1994

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   Statutory Framework
                                                                      EIA Guidelines for Mining
   wastes are subject to applicable State requirements.  The remaining two wastes (phosphogypsum and
   phosphoric add process waste water) are currently being evaluated under the authority of the Toxic
   SufS,tai^e?l	£2552!	^S	ffSCA)	to^investigate pollution prevention alternatives.  Five specific wastes
   F*\ ffl**,** hazardous wastes and must be managed as such; other than these and the 20 wastes
   exempted in 1991, mineral processing wastes are subject to regulation as hazardous waste if they
   exhibit one or more hazardous waste characteristics.
  EPA interprets the exclusion from hazardous waste regulation to encompass only those wastes that are
  uniquely related to the extraction and beneficiation of ores and minerals. Thus, the exclusion does
  aot apply to pastes ..... *itt ..... nay ..... t» ..... §enaated # a mine site ..... but ...... Oat ...... are ...... not, ..... unjquely associated with
  mfapng.  For example, waste solvents are listed as a hazardous waste under 40 QgR, §261 .3 1
  (Hazardous '^Hastes frpni Nonspecific Sources). They are generated at mining sites as a result of
  cleaning metals parts.  Because this activity (and this waste) is not uniquely associated with extraction
      beneficiatio° operations, such solvents must be managed as are any  other hazardous wastes,
         to ft, *$&* f equirements m 4° CFR Vaits 260 through 271, or State requirements if the
      ..... j* ...... autho nzg ..... to ....... hnDtenent ....... the ..... RCRA ....... Subtitle ...... C program.  In practice, most, mine sites generate
  relatively small ff111!168 of hazardous wastes.  There are a few large coal and noncoal mines,
  however, that generate large quantities and thus may be regulated as hazardous waste  treatment,
  storage, or disposal facilities. In these cases, the units in which exempt  wastes are managed may be
  subject to the requirements of 40 CFR §264.101, which require corrective action at certain solid
 waste management units at regulated facilities.                              .
"sfacf .....   ,
 numer o
               ]Ru1^^
                   to
                                       ........      .....     ,,,,^      ...... (OSW) ...... has ....... undertaken ...... a ................................. '
                             5^ programs and to enhance EPA's understandmg of the mining
         |i ......            ...... environmental  ingacts. .............. To ....... identi^'and'^fbcus^discussipn on the key
 technical and programmatic issues of concern, ipA developed staff-level approaches to regulating
 mining wastes under RCRA Subtitle D that were widely reviewed and discussed. EPA also
 established a Policy Dialogue Committee under the Federal Advisory Committees Act to facilitate
 discussions with other Federal agencies, States, industry, and public interest groups. Grant funding
 vns iwvided to the Western <5ovemors' Association to support a Mine Waste Task Force, which has
 fostered the refinement of State programs  that regulate mining operations, allowed coordinated
 discussions among States of mining-related issues, and commissioned a number of technical studies.
 Gran^ funding also has been provided to several States for developing and enhancing mining-related
programs and to educational institutions for technical investigations.
OSW

              continued its investigation of the. mining industry. EPA is currently preparing detailed
profiles of a number of mining industry sectors.  These profiles are intended to represent current
extraction and beneficiation operations and environmental management practices, and applicable
Federal and State regulatory programs.
                                            6-18
                                                                             September 1994

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 ELiL Guidelines for Mining	   .	Statutory Framework

 In addition, OSW visited a number of mine sites and prepared comprehensive reports on the
 operational, environmental, and regulatory characteristics of the sites. Together with the profiles,
 reports on visits to mines in specific industry sectors are being compiled into Technical Resource
 Documents.  OSW also has compiled data from State regulatory agencies on waste characteristics,
 releases, and environmental effects; prepared detailed summaries of over 50 mining-related sites on
 the Superfund National Priorities List (NPL); and examined a number of specific waste'management
 practices and technologies,  including several currently available pollution prevention practices
 technologies.  EPA has also conducted studies of State mining-related regulatory programs and their
 implementation. Finally, EPA has undertaken a number of technical studies, including investigations
 of prediction techniques for acid generation potential, tailings dam design, closure and reclamation of
 cyanide heap leach facilities, and other topics.  (Profiles and technical studies, currently in draft form,
 were used extensively in preparing these guidelines).

 6.4    .ENDANGERED SPECIES ACT

 The Endangered Species Act (ESA) (16 U.S.C. §§1531-1544) provides a means whereby ecosystenii
 supporting threatened or endangered species may be conserved and provides a program for the
 conservation of such species.  Under the ESA, the Secretary of the Interior or the Secretary  of     :
 Commerce,  depending on their program responsibilities pursuant to the provisions of Reorganization
Plan No. 4 of 1970, must determine whether any species is endangered or threatened due to habitat
destruction, overutilization, disease of predation, the inadequacy of existing regulatory mechanisms,
 or other natural or manmade factors.  When the Secretary determines that a species is endangered or
threatened, the Secretary must issue regulations deemed necessary and advisable for the conservation
of the species.  In addition, to the extent prudent and determinable, she or he must designate the
critical habitat of the species.                      .

Section 7 of the ESA requires Federal agencies to ensure that all federally associated activities within
the United States do not have adverse impacts on the continued existence of threatened or endangered
species or on critical habitat that are important in conserving those species.  Agencies undertaking a
Federal action must consult with the U.S. Fish and Wildlife Service (USFWS), which maintains
current lists of species that have been designated as threatened  or endangered, to determine the
potential impacts a project may have on protected species.   The National Marine Fisheries Service
undertakes the consultation  function for marine and anadromous fish species while the USFWS  is
 responsible for terrestrial (and avian), wetland and fresh-water  species.

 The USFWS has established a system of informal and formal consultation procedures, and these must
 be undertaken as appropriate in preparing an EA or EIS. Many States also have programs to identify
 and protect threatened or endangered species other than Federally listed species. As noted in Chapter
 2, 40 CFR 6.605(3) requires that an EIS be prepared if "any major part of a new source will have
 significant adverse effect on the habitat" of a Federally or State-listed threatened or endangered


                                             6-19                              September 1994

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       Statutory Framework
                          EIA Guidelines for Mining
                	I" i	!	'	'"I	I	
      species, li Federally listed threatened or endangered species may be located within the project area
            *ray, be abetted by the project, a detailed endangered species assessment (Biological
                  [ Jgay be prepared independently or concurrently with the EIS and included as an
                 States may have similar requirements for detailed biological assessments as well.
                      Illlll,j||||||i||||j||||||||||||||||||| IJIIJIII" IIIIIIIIIIIIIIIIIPIII Illllllllllllllllllllll I III* I'll	I	I	I	I	I	I	I	I	If1!1!	I	Ill1 III	ll'l "'IIIII	!	Ill	PI	ll	I	I	
                             IllliillllllllllllllllllllllllllllllllllllllllJIIIIIIillllillll illllllu IIIIIIIIIIIIIIIIIIIIIPIIIIIIIJIIIIIIIIIIIIIIIIII LI. IIJIIJII Illlllllllllllllllli JIIIIIIIJIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII illi ll.lilllll illlllJIIIIIIIIllilllillllllli illllllililllllll III i PIliLi i IIIIIII I Illllilllllllllllil,, i IIJIIIIUII. JiilIJi III, Jllllilllllllllii Illlll I i,il IJIiilllllllllllii i IllllllJIIillllliillll IIIIIIII Jl Illlll I Illllllllllllllllllllllll 1 I	II ill, II IIIII lililil, jllPIIIII I i< Jill 11111 i IIIIIIJI illlllllllilllllilii III
            [[[                   .           ......           •    ...... „
             NATIONAL HISTORIC PRESERVATION ACT
                " '    ! ill I   "1 'ti    ' '         '        i   "
                                                                            ...... ilililill ..... IIIH^^^^^^        ..... II 111 ..... Illllilllllllllllil ..... Iff,!
      The National Historic Preservation Act (NHPA) (16 U.S.C. §§470 et seq.) establishes Federal
      programs to further flw efforts of private agencies and individuals in preserving the historical and

..... sahonzeg ....... fee ...... .estabjlshmeni ....... ofjhe ...... National ....... Register'
      culttfal                                                                      ......        .......
      of Historic Places. J| establishes an Advisory Council oh Historic Preservation authorized.to review
      and comment upon activities licensed by -the Federal government that have an effect upon sites listed
      on me National Register of Historic Places or that are eligible to be listed   The NHPA establishes a
      National Trust Fund to administer grants for historic preservation. It authorizes the development of
     regulations to require Federal agencies to consider the effects Of Federal-assisted activities on
     properties included in, or eligible for, the National Register of Historic Places. It also authorizes
     tt?guiations iiiaddress|n|||i State historical preservation programs. State preservation programs can be
     approved where Armenmm ....... specified criteria. Additionally, Native; AmOT«m tribes may  •'
     assume ** fimctiorns ^ ^^ Hkto^cal Preservation Officers over tribal lands where the tribes meet
     rmnfmrnn requirements.  Under the Act, Federal agencies assume the responsibility for preserving
     historical properties owned or controlled by the agencies.
            •I iiiiiiH^^  i iiiiM       lililil I iiiiiiH^ iiiiiiiiiiiiiii 11 iiiiiii in iiiiiiiiiiiiiii i iiiii fmm\ iiiii i iiiii 11 iiiii i ill 111 ill i l iiiii iiiiiiiiiiiiiiiiii i iiiiiiiiiiiiiiiiiiliiiiii n iiiii iiiiiii nil i iiiii iiiiiii iiiiiii i ill ill 11 iiiiiiiii ill i  ill i iiiiiiiii i ill 11 	
             of amendments to the NHPA in 1980 codify portions of Executive Order 11593 (Protection
     and Enhancement of the Cultural Environment—16 U,S.C. §470).  These amendments require an
     inventory of Federal resources and Federal agency programs that protect historic resources, and
     authorize Federal agencies to charge Federal permittees and licensees reasonable costs for protection
    activities.           '
                                                                                                                  '
    Where mining activities involve a proposed Federal action or federally assisted undertaking, or
    re^u!re a license from a Federal or independent agency, and such activities affect any district, site,
    biiiMing, structure, or object that is included in or eligible for inclusion hi the National Register, the
	fEg	2	Hceosee	2S	£«	—A.dISorv Council on Historic Preservation, a reasonable
—i:!	Jffi{2i2&	£	22225	i—,iregard to ** undertaking.  Such agencies or licensees are also obligated
    to consult .with State and Native American Historic Preservation Officers responsible for
    implementing  approved State programs.
Ill 11 III I III II 111 Illlll II11 III I 111 I  l||llllllllll 111 111 111 III Illll^ III •••             I I 111 111 III IIIIIIIIIIIIIIIIII                     •Ililllllll 111 111 i ill II 111 I1 Illlll II11II III 111 Illlll  1 lililil II1 111 W       11 Hill 111 illllll''' 111 111 Pill I 111
    As noted in Chapter 2, 40 CFR 6.605(0X4)'	~~™1™l^u^^     	^JWTO"jJroES pennit"!"" •'
 	thal ^ j*vc  "significant direct and adverse	effec|	on	a property listed in or eligible for listing in the
    National Register of Historic Places" triggers the preparation of an EIS.  Many proposed mining
   operations are located in areas where mining has occurred hi the past.  Particularly in the west and
1 1

6-20
p
••••^ IIIIIIIIIIIIIIIIIIIIH Illlllllllllllllllllllll IIIIIIII 111 1111 Illlllllllllllllllllllll IIIIIIII IIIIIIII III Illllilllllllllllil IIIIIII IIIIIIIIIIIIIIII 11(111 IIIIIIII 1 1 Illllllllllllllllllllllll 1
" ' III III 1 >' 111 '
1 	 ,„ ' ' ;,
September 1994
i i iiiiii in in i in iiiii in 111IIIII iiiiiiiiiiiiiii i n ill in in ill iiiiiiiiiiiiiiiiii iiiii

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 EIA Guidelines for Mining	        •    •	Statutory Framework

 Alaska, States and localities are viewing the artifacts of past mining (e.g., headframes, mill buildings,
 even waste rock piles) as valuable evidence of their heritage.  Since modern mining operations can
 obliterate any remnants of historic operations, care must be taken to identify any valuable cultural
 resources and mitigate any unavoidable impacts. Innovative approaches are often called for and
 implemented. In Cripple Creek, Colorado, for example, a mining operation wished to recover gold
 from turn-of-the-centuiy waste rock piles. -As mitigation for removing this evidence of the area's past
 mining, the operator replaced the piles with waste rock from their modern pit.  In addition, they will
 provide interpretative  signs in the area for the public.                                    -i

 6.6    COASTAL ZONE MANAGEMENT ACT

 The Coastal Zone Management Act's (CZMA) (16 U.S.C. §§1451-1464) seeks to "preserve, protect,
 develop, and where possible, restore or enhance the resources of the Nation's coastal zone for this
 and future generations."  To achieve these goals, the Act provides for financial and technical
 assistance and Federal guidance to States and territories for the conservation and management of
 coastal resources.

 Under die CZMA, Federal grants are used  to encourage coastal States to develop a coastal zone
 management program  (CMP).  The CMPs specify permissible land and water uses and require
 participating States to  specify how they will implement their management programs.  In developing
 CMPs, States must consider such criteria as ecological, cultural, historic and aesthetic values as well
•as economic development needs. Applicants for Federal licenses or permits must submit consistency
 certifications indicating that their activities  comply with CMP requirements. In addition, activities of
 Federal agencies that directly affect the coastal zone must be consistent with approved State CMPs to
 the maximum extent practicable. The CZMA also establishes the National Estuarine Reserve System,
 which fosters the proper management and continued research of areas designated as national estuarine
 reserves.

 To the extent that mining activities are federally licensed or permitted, applicants must certify that
 such activities are consistent with applicable CMPs.                                 .

 6.7    EXECUTIVE ORDERS 11988 AND 11990

 Executive Orders 11988 (Floodplain Management) and 11990 (Protection of Wetlands) apply to
 executive agencies that acquire, manage or dispose of Federal lands or facilities; construct or finance
 construction on such lands; or conduct Federal activities or programs  affecting land use.  Under E.O.
 11988, such agencies  are required to  "...  avoid to the extent possible the long- and short-term
 adverse impacts associated with the occupancy and modification of floodplain and to avoid direct and
 indirect support of floodplain development  wherever there is a practicable alternative. . ." within the
 100-year flood elevation.  This requires that alternatives to avoid development in a floodplain be
                                             g_2i                              September 1994

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'I	!	Statutory Framework
                                                                       EIA Guidelines for Mining
            considered and that environmental impacts be assessed. If development requires siting in a
            floodplain, action must be taken to modify or design the facility in a way to avoid damage by floods.
                                                    '
   'Eao. ......... MSI ....... s
   possible the long-
       • •           •
                               short-term adverse impacts associated with the destruction or modification of
                                                                                        •
           wetlands and to avoid direct or indirect support of new construction in wetlands wherever there is a
           practicable alternative. .." When constructing a new facility, actions that minimize the destruction,
           loss, or degradation of wetlands, and actions to preserve and enhance the natural and beneficial value
           of wetlands are required. If there is no practicable alternative to wetland construction projects,
           proposed actions must include measures to minimize harm. Construction in wetlands also falls under
                of the Clean Water Act, administered by the U.S. Corps of Engineers.
                                                                                                               m	m
  The  armland Protection Policy Act (FPPA) (P.L. 97-98) seeks to
                                                                                 the conversion of
  farmland to non-agricultural uses.  It requires mat, to the extent practicable, Federal programs be
  .compatible with agricultural land uses.  The Act requires that in conducting agency actions Federal
  agencies	follow established	criteria for considering and taking into account any adverse effects such
	actions	may	have	on	farmland.	Where adverse effects are	anticipated. Federal agencies must consider
  alternatives that will mitigate any harmful impacts. Under the Act, the U.S. Soil Conservation
  Service (SCS) is required to be contacted and asked to identify whether a proposed facility will affect
  any lands classified as prime and unique farmlands. However, beyond considering potential adverse
  effects and alternatives to agency action, the Act does not provide the basis for actions challenging
       IL          11 11   ihinlllil
         programs affecting farmlands.
                 1 'I "  '  J        i         "                    • '
         RIVERS AND HARBORS ACT OF 1899
       I           !  "	              .     '           '          •	•      - '         •       •    •
  The Rivers and Harbors Act (RHA) (33 U.S.C. §§401-413> was originally enacted to regulate
  obstnKtions to navigation and to prohibit the unpermitted dumping or discharging of any refuse into a
  navigable water of the United States.  The Act also provides authority to regulate the disposal of
  dredgings in navigable waters.  The provisions of §407 forbid any discharge of any refuse matter of
  any kind or description whatever other than that flowing from streets and sewers in a liquid state.
  Under §403, a permit^is required from the U.S. Army Corps o£Ejgineers for the construction of any
  structure in or over navigable waters of the United States.  Sectionp403 is usually combined with §404
  of the(Clean Water Actl which addresses the discharges of fill to all waters of the United States.
          Federal

          63
               I             i    i                         i                    i                  '
          Since the passage of the Clean Water Act, the waste discharge-permitting fiuiction of the RHA has
                                 28 P10^13111 under §402 of the|CWA.  Nevertheless, some" provisions of the '
          RHA, primarily Sections 403, 404, and 407, could still be used to enforce single-instance waste
                              navigation and anchorage.

                                                                        r'iilillllllii'i'WIilil
                                                                               •If1!11 I'll1'III,
                                                                                                    !SE!!!!iZI	    ™
           "111!	!'l"l
      /llliliU	lilllH^       	UM^^^^^	     "       	  .
                                                                                        September 1994
                                                                      w^^^^       	,	iiri'iiiii	(iiiH^^^^^^^^^^^            	i'v^^^

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 EIA. Guidelines for Mining                              .               Statutory Framework

 6.10   SURFACE MINING CONTROL AND RECLAMATION ACT

 The Surface Mining Control and Reclamation Act (SMCRA) addresses all elements of surface coal
 operations and the surface effects of underground coal mining.  The major component of SMCRA
 relevant to new mining operations is Title V, which establishes a regulatory and permit program for
 coal mines operating after 1977.  SMCRA Title IV primarily addresses the Abandoned Mined Lands
 (AML) Program, under which coal mine sites that were abandoned prior to 1977 are reclaimed.

 SMCRA provides for delegation of program implementation authority to States, with State programs
 overseen by the Office of Surface Mining Reclamation and Enforcement (OSM) and direct OSM
 implementation in nondelegated States.  To date, OSM has delegated primacy to 23 States. In
 addition, three Native American tribes administer their own AML programs.  OSM administers
 SMCRA requirements in 13 States (most of which have no current coal production) and on all other
 Native American lands.        .

 6.10.1   PERMTTTING PROGRAM FOR ACTIVE COAL MINING OPERATIONS

SMCRA requires permits to be issued for all active mining operations. In 30 CFR Parts 816 and
 817, OSM has promulgated specific design, operating, and performance standards to ensure that
statutory performance standards are met. Special performance standards were established for: auger
mining; anthracite mines in Pennsylvania; operations in alluvial valley floors; operations in prime
farmlands; mountaintop removal;, special bituminous mines in Wyoming; coal preparation plants not
located within the permit area of a mine; and in situ processing. Some of the significant standards
covering surface and underground operations include:

     •   Surface Resources

             Disturbed areas must be returned in a timely manner to conditions that support the land
             .use(s) of the site prior to mining or to a "higher and better use."  Land uses include
             industrial, agricultural, fish and wildlife habitat, or combinations of land uses.

             Backfilling and grading to achieve approximate original contour (AOC); AOC includes
             elimination of highwalls, spoil piles, and depressions.  Exceptions to AOC requirements
             are permitted for mountaintop removal operations and mines that are considered to
             operate hi thick or thin overburden conditions.

             Exposed coal seams and combustible, toxic, or acid-forming materials must be  covered
        •  -   with a minimum of four feet of suitable material.

             Reclamation/revegetation requirements include that a permanent, diverse and effective
             vegetation cover of native plants be established that will support the postmining land
             uses.
                                           6-23                            September 1994

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             Statutory Framework
                                                                                 EIA Guidelines for Mining
    hi1'1!	I	II	
                  *   Water Resources

                          Mining should be conducted to minimize disturbance to the prevailing hydrologic
                          b|knc^, tp prevent long-term adverse impacts. Changes in quality and quantity of
                          ground and surface water must be minimized. Protection of the hydrologic system
                          requires that runoff from all disturbed areas (including those that have been regraded
                          and seeded) pass through a sedimentation pond prior to discharge.  Sediment ponds
                          must be designed to retain at least the 10-year 24-hour precipitation event. Effluent
                          limitations have been established under the Clean Water Act, as discussed in Section
                          6.1 above.
                              1             »      i
                     -	jpn	The groundwater recharge capacity of reclaimed lands must be restored and backfilled'
                         materials must be placed to minimize impacts to flow and quality of the aquifer.

                     -   Alluvial valley floors west of the 100th meridian must be restored to their full
                         hydrologic function, including gradient, shape, capillary and perched water zones, and
                         moisture-holding capacity.
                I                                                    * n
Illlll  IIIH        Inn   i  i      m i i   i           ii  i i         i in i     i      i i n  i   i  nn 11      in         m	  ui	<	
  _          Permits can be issued only if a mine can be successfully reclaimed.  Along with permit applications,
         •   applicants must submit reclamation plans that include approaches to addressing all environment risks
            identified in the application.  Permit applications must be denied if the operator (or corporate
                                other site in the country, unabated violations of SMCRA or other environmental
           affiliates)	has,	at
           laws.  In addition, permits can be denied or revoked if applicants or permittees have shown a
           consistent pattern of violations, again at any site.  The Comprehensive National Energy Policy Act of
           1992 provided	for	an^era^dmj&cm	die 'permit prohibition process' at SMCRA" §510(c). ' 'This'
iiiiiiiiiiiiinnnnniiiiiiiinininn iiiiiiii iininiinnni iiniinn
                |  .     '   ....   | |    i •  ,i' •»"    ,     HI • , , • ,r   '  , i,1    i'      ,   ',',,  . ',    i'     ' ,   i ,,|| j,,            •
           exemption specifically iapplies	to	authorized	reininuig sites where vjplatipns of permit conditions occur
           due to "unanticipated events."  The exemption does not preclude the permitting  authority from taking
           other enforcement actions, however.
                           i,                                                            1

           SMCRA	specifically requires that	discharges	to	surface	waters	be	in	compliance with applicable State
          ^and Ifcdera]	wate^	quality regulations and the coal mining effluent -guidelines at 40 CFR Part 434.
          	Several	of the	design	reqmreinents	under	30	CFR	Part	816	also pertain to controlling discharges from
           active mining areas.  Permittees are specifically required to design and install sediment/siltation
           control measjues that represent  the "Best Technology Currently Available (BTCA)." For sediment
           control, BTCA originally consisted of controlling discharges from disturbed areas through
           sedimentation ponds.  This uniform approach was challenged and BTCA determmatipns are now made
           on a case-by-case basis.
                                                                               il iiiiiii n in n mill n iii||iiiiiiiil|iiiiiiiiiiilliii
           SMCRA requires reclamation bonds for all sites. The basic requirement is a bond for the full cost of
           site reclamation, although "OSM can approve alternative bonding approaches if they are deemed
           adequate.  Alternative approaches such as fixed amounts per acre disturbed have been adopted by
      	some, States.
                                                                 Illlllllllllllllll I IIIIIIIIIIII IIIIIIII IIIIIII IIIIIIII IIIIIII^    illiilllllilillllll 111 ill 1111 I 111 I) il    „  ill1 II111 111 I ll
                                                       I iiiiiiiiiiii 111 linn ui nil iiiiiiii
                                                        6-24
                                                                                           September 1994

                                                                                          inn in iiiiiii iiiiiiii i iiiiiiiiiiiniini ii nn n in i iii iinninniiiinnnnnnniiiinniiiiniinnnnnnnni|ii  iiiiiiiiiiiiiiiiii in n i iiiiiiii n ninnn||li
                                                                                            n                	      -   In

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 EJA Guidelines for Mining	     Statutory Framework

 In practice, reclamation plans and bonding requirements have emphasized land restoration (i.e.,
 recontouring and revegetation) rather than water quality issues (except for impacts from erosion).
 Following reclamation and full bond release, any point source discharges of pollutants remain subject
 to NPDES permitting. However, NPDES permits have not generally been required following
 reclamation and bond release (i.e., after discharges are not subject to effluent guidelines). The
 NPDES storm water program has followed this lead:  sites that have been reclaimed after SMCRA's
 enactment are not subject to the program. Lusome cases, operators have forfeited bonds that were
 inadequate to reclaim sites (and to address water quality).  The responsible party for any remaining
 discharges is a matter of some contention at the present time; under the storm water program, the
 owner of the site would be responsible for obtaining a permit for point source discharges of
 contaminated storm water.

 A limited exception to EPA's 40 CFR Part 434 effluent guidelines was provided in the Water Quality
 Act of 1987, which allows modifications to the National technology-based limits in cases where
 remining abandoned sites will result in the potential for improvement of water quality. Where such
 exemptions are granted, technology-based limits are based on the permit writer's best professional
judgment.  Limits on pH, iron, and manganese cannot exceed the levels discharged prior to remining;
 discharges also cannot violate applicable water quality standards and criteria under §303 of the Clean
 Water Act.  Pennsylvania is notable for having used this provision to encourage remining of problem
 sites, and other States are increasingly using or considering the provision.

 It should be noted that certain provisions of SMCRA and the Clean Water Act may provide
 disincentives to remining abandoned coal sites.  For example, neither SMCRA standards nor the
 effluent limitation guidelines established under the Clean Water Act distinguish between remining
previously abandoned sites and mining undisturbed land (except as noted above). To the extent that
there is a greater potential for noncompliance at remining sites (e.g., because of greater complexity or
unpredictability of the hydrogeologic regime), the "permit block" provisions of SMCRA (§510(c))
could be a disincentive to remining: failure to comply with an NPDES permit can prevent die
operator from obtaining future SMCRA permits.   The relative stringency of water quality standards,
particularly forpH, also may prevent operators from remining sites, since permits must provide for
attainment of water quality standards and criteria, notwithstanding any prior nonattainment. (To the
extent that water quality standards and criteria act as a disincentive to remining, this may increase as
numeric criteria are established for an increased number of toxic pollutants hi response to the  1987
amendments to §303.)

6.10.2  ABANDONED MINE LANDS PROGRAM

Title IV of SMCRA established the Abandoned .Mine Lands (AML) Program to provide for
reclamation of mine sites abandoned prior to 1977 (the date of enactment).  The program was
subsequently amended to allow the expenditure of funding to reclaim post-1977 operations where an


                                            6-25                              September 1994

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                                            1 iiiiiiiiiii iiiiiiiiiiii  	iii iiiiiiiiiii iifi iiin^^^  iiiiiiiii 'iiiipn
        Statntoiy Framework        	;	      EIA Guidelines for Mining

	I	!	:	if	1	;	:	!	-	'	:	i;	!	!	:	:
        abandonment occurred between 1977 and the date of State program approval and the
        reclamation/abatement bond was not sufficient; or where a surety provider became insolvent and "
        available funds were not sufficient to reclaim the site. The AML program is supported by the
        Abandoned Mine Reclamation Fund.  The fund receives reclamation fees paid by active mining
        operations: for lignite coal, the contribution to the fund is IOC per ton; for other coal, the fee is 150
        per ton of coal from underground ^^ ^j |^ per.ton ,,g|,,,,s^ac^rnine	coal.	The fund is	currently '
        authorized to collect fees through the year 2004.   '
       6.11   MINING LAW OF 1872
                  ™' ~  .....    '       .....
                  ......    ......  , .....    ....... 22 ....... 2;2£,; ......... ,11, .......         .....
       United States can explore and purchase mineral deposits and occupy and purchase the lands on which
       such claims are located. The basic provision of the law provides that:
             I II     llllllllllllllllllllllllllllll llllllllllllllllllllll|llllllllllllllllll lllllllllllllllllllllllllllllll llllllllllllllllllllllllll llllllllll II lllllllllllllllllll llllllllllllllllllll II lllllllllllll   Jl   I      n   i, i n ,1 ^  *^

            Except as otherwise provided, all valuable mineral deposits hi lands belonging to the
            U.S  . ........ g ......... g ....... shall ...... Jg ...... fteg ..... and ...... open to exploration and purchase, and the lands in which they
           1 iigg ..... igSSsfi ...... SSSS3&&* ..... and-puidiase, by citizens  of the, U.S. . •. . under regulations  •
            prescribed by law, and  according to the local customs or rules of miners hi the several
            mining districts, so far as the same are applicable  and not inconsistent with the laws of the
            U.S.     •         '                          >.,.,,            ......       ;,
                           !»  . •   .          • '    !       ,. •     '" I     ,      '     :•••'.
         e Mining Law establishes the basic standards for the location, recordation, and patenting of mining
      ..Claims,     cneral, ....... Persons ....... «[e ...... authorized ..... to ...... enter ..... Federal ....... lands ....... and ...... establisJi ...... gr ...... locale, ..... i ...... cjajm ..... to a
                                                         IS* ,5°.w, ,§, SISSl/SojS, JSSlSSd Somber, as
                      ............... SSSm ..... 1 ..... illi ..... ii§ ...... 1&&SSSS& ....... JSS??, ....... &5i ....... SEES ........ !,?I5s ........ FS-oided ...... Hlltl ...... 1LM), the
                fns: ..... a j»ss«Kigrxgt ..... to ^.laml fi« i£urposes_ rf mine^ devdogmait and ,1161631161;
               e ...... clSn ...... fsmall ....... amounts ....... p| devdppment work'is done or small fees are paid.  Upon proving
      that a valuable mineral deposit has been discovered (this proof must meet regulatory standards), claim
      holders may -patent the claim and purchase Ae land for riom^ sums.  Except as specifically
      authorized by law (e.g., certam mholdmgs), land management agencies have no further jurisdiction
      ove£ j^d kads- MffSi t*??05' whether patented or not, are fully recognized private interests
               *                              55EE1!5! ...... S ...... SSlES! ..... IP^Y^te, P10?6^ subject . to Fifth
                                                                                    '
     .......   .....    ......   .....      iij   ..... a  .............   .....       ,   ......       ......  ......          .....      ,               .
     ....... 'Amendment jixotectira .against tal^gs by the United States without just compensation. .' The standards
      set in the Mining law may be supplemented by local%law not hi conflict with the Mining Law or State
      YMW*
      law.
                          ,                                     .
          	yarious^ws	have	resoicted	the	minerals	that	are	subject, to location, under the Mining
     Law; restrictions were generally not retroactive but were subject to valid existing rights.  "Locatable"
     minerals subject to location "of claims undgr the Mining Law now include most metallic mhierals
     (except uranium) and some nonmetallic minerals. In addition, certain Federal lands have been or may
               to mineral development, subject to valid existing rights (these include the National Parks
                                ,i                               ..                 >i

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  EL4 Guidelines for Mining  	 	Statutory Framework

  and National Monuments, among, other lands). In addition, only "public domain" lands are generally
  open to mineral location under the Mining Law.

  Only since 1976 have claimants been required to record claims with BLM.  Through the end of fiscal
  year 1991, more than 2,700,000 claiiris had been accepted for recording by BLM. Of these, more
  than 1,500,000 had been abandoned, relinquished, or rejected, leaving more than 1,100,000
  unpatented claims on Federal .lands.  The number of claims on which significant prospecting or
  mining occurred prior to 1976 is simply unknown, since there were no reporting (and few other)
  requirements at the time.

  6.12  FEDERAL  LAND POLICY MANAGEMENT ACT

  The Federal Land Policy Management Act (FLPMA) (43 U.S.C. §§1701-1782) provides the Bureau
  of Land Management with authority for public land planning and management/ and governs such
 disparate land use activities as range management, rights-of-way and other easements, withdrawals,
 exchanges, acquisitions, trespass, and many others. FLPMA declares it to be the policy of the United
 States to retain lands in public ownership (i.e., rather than "disposing" of the lands by  transferring
 ownership to private parties) and to manage them for purposes of multiple use and sustained yield.
 Under §202, BLM must develop and maintain plans for the use of tracts or areas of the. public lands.
 To the extent feasible, BLM must coordinate its land use planning with other Federal, State, and local
 agencies. BLM also must provide for compliance with "applicable" pollution control laws (including
 Federal and State air, water, and noise standards and implementation plans) in the development and
 revision of land use plans.  The overall protective standard is provided in §302(b), under which BLM
 is to take any necessary action, including regulation, to prevent "unnecessary or undue degradation"
 of public lands.  Subject to this and several more limited exceptions, nothing hi FLPMA "shall in any
 way amend the Mining Law of 1872 or impair the rights of any locators of claims under that Act,
 including, but not limited to, rights of ingress and egress" (§302(b)).

BLM regulations (43 CFR Group 3800) impose a number of broad requirements upon operations on
mining claims on BLM-managed lands,  but contain few specific technical standards.' The basic
compliance standard is that operations must be conducted so as to prevent unnecessary or undue
degradation of the lands or their resources,  including environmental resources and the mineral
resources themselves. According to 43  CFR §3809.0-5(k), "unnecessary or undue degradation"
means surface disturbance greater than what would normally result when an activity is being
accomplished by a prudent operator in usual, customary, and proficient operations of similar character
and taking into consideration the effects of operations on other resources and land uses,  including
those resources and uses outside the area of operations.  Failure to initiate and complete reasonable
mitigation measures,  including  reclamation of disturbed areas, may constitute unnecessary or undue
degradation.  Finally, failure to comply  with applicable environmental protection statutes and
regulations constitutes unnecessary and undue degradation.
                                            6-27                             September 1994

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             Statutory Framework
         EIA Guidelines for Mining
                 's implementing regulations pertaining to development of mining claims include three levels of
            review:
                     Casual use—for which no notification or approval is necessary
                         	r"	!	~	!	:	"	:	"	;	'	:'	:	:	""	'	""	: ,u	:	:	  ' i       i       	!	'	:	
                     Notice-level—for cumulative annual disturbances total less than five, acres.  Operators must
                     notify BLM officials (and commit to reclamation), but no approval is required.
                     Consultation may be required if access routes are to be constructed.

                     Approval-level—for disturbances exceeding 5 acres hi a calendar year or hi certain
                     specified	areas	(wilderness	areas,	wild	and	scenic	rivers,	.critical,	.habitat, areas of the
                              	DeseS	Conserotion Areg.	Operators must obtain BLM approval (within
                                        	gf -	pjan of Operations for such operations.              '   •   "
                   be taken to prevent undue and
                                                       te ...... and ...... &e.proj»sed operation, deluding measures
                                             	salvaging topsoil for later use, erosion and runoff control, toxic
                                             ":'l!i|l|ll	:i':"jii|ij	I'll .'SIIIS11-! HI .|, i|L< ifi • f 	, , i   .. , , ,	„,.	,  |,,f,	,  , „,, „	 ,T 	,„	 , '   ,	
                                                                            il, and reegetation (where
                                         require operators to furnish bonds (site-specific or blanket) or cash
          	"	f	jii	''	!	='!	J	i"" i" '          ,  i,'''"'',        i  : •••',•     : " iii," "*     ' - i. . '  ,  ,  •• •*.,
           deposits, with-the amount left.to die responsible official (policy now calls for full reclamation bonding
           for cyanide and other chemical leaching operations, and a similar policy is anticipated to be issued hi
               • for potentiallv acid-generating mines). Following approval of a plan of operation, BLM may

                             an to ensure that the approved plan is being followed. Failure to follow approved
f^i.^^^^	£?£|>«ations, or to reclaim lands; may result hi a notice of noncompliance, which hi turn can
                            may be modified at BLM's .request or at the... operator's behest. . Significant
                                                            of
are reviewed ...... by BLM "hi  e context of the requirement to prevent
              e for 'reasonable reclamation^ ........ (|3809.1^(a)).  Wubin
             tbe plan
» cnan
                                                                                                Plan
                                            EsZ re^uired fot review; that the pjmramot ..... be ...... approved until
                                             EPA; dr that the plan cannot be approved, until BLM complies
                  Endangered Species Act or National Historic Preservation Act or consults with other surface
          managmg agencies. (Should cultural resources be discovered during an inventory, BLM is
          responsible for any costs of salvage that may be necessary.)
       	,	=	y2£3!!i	fiflisgEEi.Pj3!!	°!	PI?*3!!?!!?	|°I	piodjf|ca||o:n),> BLM must ojnduct .an, .enyjroninen|al '
       i£^^^^O^	sup|)!eii5iO.  this EA| is used to ..assess the adequacy of proposed .mitigation measures
       ^ti&	reclamation procedures	to^pjev^unnej^sary and undue degradation.. The EA then leads to a
I^JjjjJ3S|	^^.S^Sg	liili	S?H	°r:	^l°M	llE^iSEl	S,,!2	fclS3^?.,^30,?1?,3^

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 EIA Guidelines for Mining.	""	    Statutory Framework

 Record of Decision. If the proposed operation is to be issued a new source NPDES permit and is in
 a State where EPA is the permitting authority, or if in other cases where EPA has significant
 environmental concerns, EPA typically becomes a cooperating agency in the NEPA process.

 There are a number of issues related to plans of operations and BLM regulatory oversight that bear
 noting. For example, plans of operations themselves become the "permit" to which operators must
 adhere. These are often enormous multi-volume documents that reflect the uncertainties of mining:
 they often note multiple contingencies in the event that specific conditions are found or develop.
 Detailed descriptions of planned operations under each contingency are not generally feasible (and are
 certainly not economic).  As a result, plans provide appropriate caveats that additional plans,
 consultations, studies, or modifications will be made if necessary. It is not practical to modify plans
 of operations with every such change, and even when plans are formally modified, they often address
 only the modification, not the entire operation.  Thus, a mine that evolves over time, as most do,
 comes to resemble the original plan less and less, and determining exactly which modification
 addresses  a particular mine component can be extremely difficult. In addition, BLM administration of
 its regulations is very decentralized, with State offices and local resource area offices generally
 responsible. This recognizes the site- and region-specific nature of the mining industry, and its
 environmental impacts, but has led to inconsistency in several areas, including the level of
 "significance" that triggers preparation of an environmental impact statement. Environmental impact
 assessments (whether in EAs or EISs) follow the same pattern as plans of operations: they often
 address the plan or modification at hand, not necessarily the entire mining operation as it has grown
 and evolved over time. Finally, BLM considers itself extremely constrained by the Mining Law;
there is no provision for BLM disapproval of proposed plans of operations, only the prevention of
unnecessary and undue degradation of public lands.

6.13   NATIONAL PARK SYSTEM MINING REGULATION ACT

The National  Park System Mining Regulation Act (also known as the Mining hi the Parks Act, or
MPA) (16 U.S.C. §§1901-1912) reconciles the recreational purpose of the National Park System with
mining activities affecting park lands.  The Act subjects mining activities within the National Park
System to such regulations as deemed necessary by the Secretary of the Interior. It also required that
all mining claims within the park system be recorded by September, 1977, or become void.

The National  Park Service has extensive regulations governing exercise of valid existing mineral
 rights (36  CFR Part 9 Subpart A). The  regulations restrict water use,  limit access, and require
 complete reclamation.  They also require that operators obtain an access  permit and approval of a
 plan of operations prior to beginning any activity.  A plan of operations  requires specific site and
 operations information, and may require the operator to submit a detailed environmental report.
 Operators must comply with any applicable Federal, State, and local laws or regulations.
                                                                                     4
                                            6_29                              September 1994

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	;	IP	;i	;	                                   ;	)	;	i	•;	;	;	

             Statutory Framework
                                        EIA Guidelines for Mining
                                   1? MULTIPLE USE AND SUSTAINED YIELD ACT; NATIONAL
                    FOREST MANAGEMENT ACT
             The Organic Act of 1897 (16 U.S.C. §§473-482, 551) has governed the Forest Service's activities
             Sge	fhe	SSliSSf,	^y8 of National Forest management. The Act delegated broad' authority over
             visually all forms of use hi the National Forest System.  It also provides for continued State
            jurisdiction over National Forest lands.  Finally, it declares that forests shall remain open to
           *  prospecting, location, and development under applicable laws, and that waters within the boundaries
             of the National Forests may be used for domestic mining ami milling, among other uses.

            The Multiple Use and Sustained Yield Act of 1960 (MUSYA) (16 U.S.C. §§528-531) establishes that
            the National Forest System is to be managed for outdoor recreation, ranee, timber, watershed, and
           	I	IIIIIIIIBIIIIIIIIIIIIIIIIIIIIII    '!"    ''l         I         I          I        II        i 	,	i	in	a	i	'	'
                • and wildlife purposes, and that these purposes are supplemental to the purposes for which the
                    forests were .established as set forth in the Forest Service Organic Legislation (16 U.S.C.
            1§475,477, 478, 481, 551).  MUSYA provides that the renewable surface resources of the national
                   are tQ,be administered for multiple use and sustained yield of products and services. Nothing
     ":^—:i& MUSYA J8 ^ea^' to affect the use or administration of the mineral resources of the national

            forest lands. (16 U.S.C. §528).  Section 530 of the MUSYA authorizes the Forest Service to
           	IBB^I   I        ' I   I II     I     .        *             I i I  I   I  11 I I I        III |   I I
            cooperate with State and local governments in managing the National Forests. MUSYA is
            implemented by the Secretary o| —^i^^^  —^ Nat.onaj porest Management Act of 1976 provides
            the .Forest Service with authorities and responsibilities similar to those provided to BLM by FLPMA.
           It establishes a planning process for National Forests that hi many ways parallels the process
           gt&Iished	under FLPMA. for BLM lands.
             1 ' i
     Ililtli 'I "I iilllli '
                                                           ..... lllf 111 1 1| I ill i Iliiilillll lili Iliiliii III ..... ill •     i liiillili II IIIIIIM I Nil 1 1 111 |jl|i|( ..... I lit 1 11   ill 1 1 111 1 .
25 ..... £2 ..... 22 ...... 22


                                                                                                   few
                                                                                           ,
           IgSfic technical standards. In all cases where the land's surface is to be disturbed, operators must
           ijiii ................................... I            i     ^^               i                           I   II  f
           file a notice of intent. For significant disturbances (i.e., where mechanized equipment or explosives
           .............. .................... •• ...... Jll   |     I    II  III III II           llll                   ............... I ....................... ................... ami [[[ limill! ..... I .................................. ••"* ................ *C ..... m ..... [[[ ' .............................. ".  .,
           are to be used), ....... operators ..... must submit ..... a proposed plan of operations. Forest Service regulations
                  ing plans of operations and then* review and approval, reclamation standards, and
                         review are similar to thosetdescribed "fm gy  ......      ............... £jj  |BLM'si'iiregulations, they
                                                                              |i
           require compliance with the Clean Water Act and other environmental statutes and regulations.



                                                                                           Ull 111
                  MINERAL LEASING ACT; MINERAL LEASING ACT FOR ACQUIRED LANDS
                                                                                                          iiiiiiiii
               |Minena Leashig Act of 1920 (MLA) (30 U.S.C. §§181-287) and the Mineral Leasing Act for
                    Lands (1947) (30 U.S.C §§351-359) created a leasing system for coal, oil, gas, phosphate,
           lid pertain other fuel and chemical minerals ("leasable" minerals) on Federal lands.  In addition,
           Sectpn 402 of Reorganization Plan No. 3 of _ 1946 (and other authorities) au&orizes leases for
                   minerals on certam ks : (e .g., some acquured lands, as opposed to public domaui lands).

-------
 EIA Guidelines for Mining   	,	        Statutory Framework

 mineral development.  The Department of the Interior has promulgated extensive regulations
 governing various aspects of leases.  BLM may issue competitive, noncompelitive, and preference
 right leases that set the terms, including environmental terms, under which mineral development can
 take place. Prior to lease issuance, BLM must consult with the appropriate surface managing agency
 (e.g., the Forest Service), and for acquired lands must have the written consent of the other agency.
 Regulations require compliance with Federal and State water and air quality standards, and failure to
 comply witn lease terms can result in lease suspension or forfeiture. At the end of fiscal year 1991, a,
 total of 69 nonenergy mineral leases (more than 49,000 acres) were in effect; hi addition, there were
 475 coal leases in effect, covering nearly 700,000 acres of public domain and acquired land.

 6.16   COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION,  AND
        LIABILITY ACT

 The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) (42
 U.S.C. §§9601-9675) established the  Superfund program to deal with releases and threatened releases
 of hazardous substances to the environment.  CERCLA provides funding and enforcement authority
 for Federal and State clean-up programs at thousands of sites throughout the United States that are
 contaminated due to the release of specified hazardous substances. The statute establishes notification
 requirements for releases of hazardous substances in reportable quantities (RQs), provides abatement
 and response authorities for situations where a substance or pollutant may present an imminent and
 substantial danger to the public health or welfare, requires the development of a National Contingency
 Plan (NCP) designed to provide for consistent and coordinated responses (both removal and remedial)
 to hazardous substance discharges, and creates a Hazardous Substance Response Trust Fund
 (Superfund) to pay for emergency removal actions and long-term remediations at abandoned sites
 where liable parties cannot be identified.  CERCLA establishes that owners and operators of
 contaminated sites, as well as waste generators and others who were responsible for waste disposal
and waste transportation are subject to strict, joint, and several liability for response costs and natural
resources damages.  The statute also establishes site cleanup standards.

Over 52 mining- and mineral processing-related sites are currently on the NPL, including some of the
largest and most complex of all NPL sites. The cleanup standards applied to specific NPL sites are
determined on a site-specific basis, following detailed studies of the site, the potential and actual risks,
and possible remedial actions. Because the United States is the land owner at several of the mining-
related NPL sites, Federal agencies are responsible persons in some cases..

It should also be noted that several Federal courts have addressed the issue of whether mining wastes
are "hazardous substances" under CERCLA, and thus whether mining sites where releases  of mining
wastes occur are subject to CERCLA removal or remedial actions. The basic question is whether the
exemption of mining wastes from regulation as hazardous wastes under RCRA excludes them from
the definition of "hazardous substance" in §104(14).  In Eagle Picher Industries v. EPA (245 U.S.
                                            6-31                              September 1994

-------
 I	IIIIIHI	lilii'll	Ill11'' liliil	1L.	•- •-	—	
	Statutoiy Framework
                                                                               EIA Guidelines for Mining
             . D.C. 196, 759 F.2d 922 (D.C. Cir. 1985), it was determined that mining wastes exempt from
                   waste Regulation ..... w,e,E ...... H!§5! ..... §£ ..... CERCLA ...... definition ...... of hazardous ....... substances.  There has
         been additional judicial consideration of this issue, with the decisions generally consistent with the
         Eagle Picker decision.
            I   .        '     i                        •                              .
      I I II II |l|llll|ll 111 111 I ill ill IH          (IIIIIIH         111 II  111 I I 111 ,      1111 111 1(11 II I III 1 1 lllllIH           1
         Issuance of an N^P permit for a discharges) from a new source mming operation can exclude the
         operator from potential  CERCLA liability. New operations are often located in historic mining
        districts, where CERCLA action may be ongoing or could occur in the future. . In such cases, the
        ievfeWCT'4c$liij?e ^P^iaNy cautious that the project will not further degrade water quality
        (mcluding sediment) and that water quality-based InTUte/requirements are included in the NPDES
        permit. Further^ prior to operation of me new source, adequate baseline data should be available to
                                                                "23$ ...... Hill ....... mmbnize. ....... any uncertainty
               to the sources of pollutant levels (PRPs versus the non-liable new operator).
    	6.17
                                  PLANNING AND COMMUNITY RIGHT-TO-KNOW ACT
        The Emergency Planning and Community Right-to-Know Act (EPCRA) (42 U.S.C. §§11001-11050)
        requires States to establish emergency response rommissions and emergency planning districts as well
        as local emergency planning committees.  These planning groups must prepare and review emergency
        plans.  The Act	ako	gqunes	that	owners	and	opentan	of facilities	who	must	su|Mn|t_materials	.safety
                      __ .i__ «     ..       - .  , ^ Health ^^ (OSHA) must
       these hazardous substances to the local ...... emergency ..... planning ...... conraittee, ...... the ...... State ...... emergency response
       commission, and the local fire department. Mining operations must report on chemical storage and
       use, and on spills or releases, to these entities.
           EPCRA also requires feculties mat
	report
                                                      , ........ Piprocess ....... certain ..... listed ...... toxic ...... chemicals to
                                          eased ..... to ..... the ..... environment ...... on ..... an annual basis,. These data
       comprise the Toxics Release Inventory, or TRI. TRI reporting requirements apply to manufacturing
       fecmtics m Standard Industrial CJassfficatipns (SIC) Codes 20 through 39.  Mining operations are not
       whfairt these SIC codes and thus are not subject to TRI reporting. However, it should be noted that
               i«* ~t „».     i    j *—-.    _, of feciiities required to report releases are currently being
                 ......           ......            .......
       expanded or considered for expansion by EPA.
            i
       6.18   WELD AND SCENIC RIVERS ACT
            If                      .
       The TjVild and Scenic Rivers Act of 1968 (16 U.S.C. 1273 et seq.) provides that «[c]ertain selected
       rivers . . . shall be preserved in a free flowing condition, and that they and then- immediate
       *aivifoliments ska1} ^ protected for the benefit and enjoyment of present and future generations.;'
       Section 7 of the Act prohibits the issuance of a license for construction of any water resources project
       that \yould have a direct adverse effect on rivers (or reaches of rivers) that have been selected on the
lillliNllliL    '(niiillili IIIIIIH
                                                 '
                                                      6-32
                                                                                   September 1994

-------
 EIA Guidelines for Mining        ' _ _ Statutory Framework

 basis of their remarkable scenic, recreational, geologic, fish and wildlife, historic, cultural, or other
 similar values for the National Wild and Scenic Rivers System.

 The System includes rivers and streams placed in the System by acts of Congress and rivers that have
 been studied and deemed to be suitable for inclusion. Any potential impacts on rivers and streams in
 the System must be considered, and direct adverse effects on the values for which the river was
 selected for the System must be prevented.

 States also have their own systems for protecting rivers and streams or portions thereof. While EPA
 has no legal requirement to' consider State-protected wild and scenic rivers and streams, any potential
 impacts to such areas should nevertheless be considered and addressed.

 6.19    FISH AND WILDLIFE COORDINATION ACT

 The Fish and Wildlife Coordination Act of 1934 (16 U.S.C. 661 et seq., P.L. 85-624) authorizes the
 Secretary of the Interior to provide assistance to, and cooperate with, Federal, State, and public or
private agencies, and organizations in the development, protection, rearing, and stocking of all species
of wildlife, resources thereof, and their habitat.  The majority of the Act is associated with the
coordination of wildlife conservation and other features of water-resource development programs.

6.20    FISH AND WILDLIFE CONSERVATION ACT

The Fish and Wildlife Coordination Act of 1980 (16 U.S;C. 2901  et seq.) encourages Federal
agencies to conserve and promote conservation of nongame fish and wildlife and their habitats to the
          extent possible within each agency's statutory responsibilities.  The Act places no
affirmative requirements on Federal agencies.

6.21   MIGRATORY BIRD PROTECTION TREATY ACT

The Migratory Bird Protection Treaty Act (16 U.S.C. 703-711) prohibits the killing, capturing, or
transporting of protected migratory birds, their nests, and eggs. Consultations with the Fish and
Wildlife Service are encouraged if project activities could directly or indirectly harm migratory birds.
                                            6-33                             September 1994.

-------
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                 •1111111   II11  ^ti\t\ IIIIIIH Illllllllllllll I lllllll      IIIIIIIIIHIIII  111II lllllll III III II1  ill I Illllllllllllll  lllllll 111 nil  11,11 111  111    II l  I     lllllll  111 '111
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                                                                                                                                                                                   II"ill   lillilllli  lIltlllH               III'    II	1
                                                                                                                                                                                    lillilllli   III II Jill lllllll 111 111 III lllllll lllllll 11111 IIIII    I  I    lllllll IIIIII I   IIIII    lllllll
                                                                                                                                                                                                                                                                                                                  ii  i    in iiiii i|ii
   lllllll  lllllllllllllllllllllllllll  I  III   lllllll IIIIII I  I lllllll   Illllllllllllll   Illllllllllllllllllll  lllllllllllllllllllllllllll  Illl lllllllllllllllllllllllllll Illllllllllllll
                                                                                                                                                                                          II   11   Illllllllllllll  II lllllllllllllllllllllllllll      lllllll|lll   lllllll  I  111  I    Illllllllllllll III     lillilllli    IIIIIIIII
111 111 11  llllllill (11111111(1111 lillilllli I   11mtmil 111 lllllll 111 I  Illllllllllllll  III lllllll 1II 111 II lillilllli 111  , II  lllllll IIIIIIIII  IM ill  111  I lillilllli III 111  Illlllllllillllllllilll lllllll illllllll III  I   III     Hi     I   lllllll 11   1II1111I1II lillilllli  i 111 IIIIIIIII 1111  1111 Hi 11	I  111 11

-------
  EIA Guidelines for Mining        	        .         .               References


                                    7.  REFERENCES


  Adamus, P.R., EJ. Clairain, Jr., R.D. Smith, and R.E. Young.  1987.  Wetlands Evaluation
       Technique (WEI); Volume U: Methodology. Operational Draft Technical Report Y-87-_, U.S.
       Army Corps of Engineer Waterways Experiment Station, Vicksburg, MS.

.  Ahsan, M.Q., et al. 1989.  "Detoxification of Cyanide in Heap Leach Piles Using Hydrogen
       Peroxide."  In World Gold, proceedings of the First Joint SME/Australian Institute of Mining
       and Metallurgy Meeting.  R. Bhappu and R. Ibardin (editors).

  Alaska Department of Environmental Conservation.  1986. A Water Use Assessment of Selected
      Alaska Stream Basins Affected by Gold Placer Mining. Prepared by Dames & Moore, Arctic
      Hydrologic Consultants, Stephen R. Braund and Associates, L.A. Peterson and Associates, and
      Hellenthal and Associates.                .  •

  Alaska Department of Environmental  Conservation..  1987 (March).  Placer" Mining Demonstration
      Grant Project Design Handbook (prepared by L. A. Peterson & Associates, Inc.). Fairbanks,   .
      AK.

 Alaska Miners Association.  1986.  Placer Mining - A Systems Approach.  Short Course, Alaska
      Miners Association Eleventh Annual Convention, October 29-30, 1986.  Anchorage, Alaska.

 Altringer, P. B., R.H. Lien,  and K.R. Gardner.  1991. Biological arid Chemical Selenium Removal
      From Precious Metals Solutions. Proceedings of the Symposium on Environmental
      Management for the 1990s, Denver, Colorado, February 25-28.

 Argall, G.O., Jr. 1987 (December).  "The New California Gold Rush." Engineering & Mining
      Journal'  30-37.                -

 Arizona BADCT Guidance Document for the Mining Category, Draft Guidance Document.  1990.
      Arizona Revised Statute 49-243 B.I., For Permitted Facilities Utilizing BADCT.

 ASARCO.  1991 (February 4).  Ray Unit Tailing Impoundment Alternative Analysis.  Appendix
      11.19. Submitted to EPA Water Management Division Region K Wetlands Program.

 Beard, R.R.  1987 (March).  "Treating Ores by Amalgamation."  Circular No. 27.  Phoenix, AZ:
      Department of Mines and Mineral Resources.

 Beard, R.R.  1990 (October). The Primary Copper Industry of Arizona in 1989.  State of Arizona
      Department of Mines and Mineral Resources, Special Report No.  16.

 Biswas, A.K., and W.G. Davenport. 1976. Extractive Metallurgy of Copper.  Pergamon
      International Library, International Series on Materials Science and Technology Vol  20
      Chapter2.                                                                    '

 Boyle, R.W. 1979. The Geochemistry of Gold and Its Deposits.  Canada Geological Survey Bulletin
      280.  Canadian Publishing Centre.  Hull, Quebec, Canada.  584 pp.
                                            7-J                             September 1994

-------
                                                                             EIA Guidelines for Mining
            Bradham, W. S., and F. T. Caruccio.  1990.  A Comparative Study of Tailings Analysis using Acid/
                 Base Accounting, Cells, Columns and Soxhelets. Proceeding of the 1990 Mming and
                 Reclamation Conference and Exhibition, Charleston, WV.

            Brady etal.  1994.  EvaluationofAcid^aseAccounting to Predict the Quality of Drainage at Surface  .
                 Coal Mines in Pennsylvania, U.S^A.  In the Proceedings of the International Land Reclamation
                 and Mine Drainage Conference and Third International Conference on the Abatement of Acidic
                 Drainage,'	April'	24r29.

       	British Columbia	AMD	fask	Force!	19891	"A^RockDn^ag"e Draft	Tedudcal	Guide,	y~J~^"}-	
                 and U.  Report 66002/2.  Prepared for the British Columbia AMD Task Force by SRK, Inc.

            British Columbia A||D Task Fpjces  1990 (August).  Monitoring Add Mine Drainage.  Prepared by
                 E. Robertson in association with Steffen Robertson and Kirsten (B.C.) Inc.  Bitech Publishing,
                 Richmond, British Columbia.        ,        ' '	\]	

           Britton, S.G., ,19923. Mine Exploitation, in SME Mining Engineering Handbook, 2nd Edition (H.L.
                 Hartman, ed.).  Society for Mining, Metallurgy and Exploration, Inc.  Littleton,  CO.

           Britton, S.G. and G.T. Lineberry.  1992b.  "Uj^rgnu^Mn^D^lppment," in SME Mining
                Engineering Handbook, 2nd Edition (ZLL. Hartman,  ed.).  Society for Mining, Metallurgy and
                Exploration, Inc.  Littleton, CO.	'	  '         	'	    ^

           Brodie, M. J., L. M.  Broughton, and Dr. A. MacG. Robertson. 1991. A Conceptual Rock
"  '          '	^i^Cjeasification	System for Waste Management and a Laboratory Method for ARD Prediction
           1	••	|l«jRnom Rock^ files.  IB Second International Conference on the Abatement of'Acidic Drainage.
                Conference Proceedings, Volumes 1 - 4, September 16,17, and 18, 1991, Montreal, Quebec.
          Broughton, L. M. and Dr. A. MacG. Robertson.  1991. Modeling ofLeachate Quality From Acid
                Generation Waste Dumps. IB Second International Conference on the Abatement of Acidic
                Drainage.  Conference Proceedings, Volumes 1 - 4, September 16, 17, and 18, 1991, Montreal,
                Quebec.              '   .    '

          Broughton, L. M.	and	Dr.	A.	MacG.	Robertson.	1,992.	AqdR^Drajnage From Mines - Where	•	
               Are WjeJJQjv.,	§tefFej|t Roberteon, and Kirsten, Vancouver, British Columbia. Internal Draft
    	Paper.      '              '    ' "       ' '             ^         •

          Bruynesteyn, A.  and R. Hackl.' 1982.  "Evaluation of Acid Production Potential of Mming Waste
             .  Materials,'" Minerals and the Environment 4(1).

          California Mining Association.  1991.  Mine Waste Management.  Edited and Authored by  Ian
               Hutchison and Richard D. Ellison. Sponsored by the California Mining Association,
               Sacramento, California.

                    Regional Water Control Board.  1987 "(April 22).  "Cyanide Requirements for Cyanidation
               Process Wastes."  Internal Memorandum from Dr. R.S. Gill to O.R. Butterfield.
                                                      7-2
       September 1994
            "£=5	!	ii!""!i:	U	
iiiiinwiiiiiiwnw^^         iiiiiiiiiiiiniw|innn i

-------
EIA. Guidelines for Mining	   '    	•    	References


California Regional Water Quality Control Board. 1993 (January 19). Personal communication
      between Richard Humphreys and Joe Kissing, Science Applications International Corporation.
      Falls Church, VA.

Clark, W.B.  1970. Gold Districts of California.  California Division of Mines and Geology,
      Bulletin 193. San Francisco, CA.

Coastech Research Inc. 1989.- Investigation of Prediction Techniques for Add Mine Drainage.
      MEND Project 1.16. la. Canada Center for Mineral and Energy Technology, Energy, Mines,
      and Resources Canada.

Cohen, Ronald R.H. and Staub, Margaret W. 1992 (December). Technical Manual for the Design
      and Operation of a Passive Mine Drainage Treatment System, prepared for the U.S. Bureau of
      Reclamation. Golden, CO.

Colorado Department of Natural Resources. 1992 (March). Guidelines for Cyanide Leaching
      Projects.  Mined Land Reclamation Division.

Cravotta, F. T.  et al. 1990. Effectiveness of the Addition of Alkaline Materials at Surface Mines in
      Preventing or Abating Add Mine Drainage:  Parti. Theoretical Considerations.  ID.
      Proceedings of the 1990 Mioning and Reclamation Conference and Exhibition, April 23-26.

Gumming, A.B. (Chairman  of Editorial Board).  1973. SME Mining Engineering Handbook. Society
      of Mining Engineers, AIME. New York, New York.

Dadgar, A.  1989. -Extraction of Gold from Refractory Concentrates:  Cyanide Leach vs. Bromide
      Process."  Presented at the Metallurgical Society Annual Meeting.  Las Vegas, NV. February
      27-Marcti 2,  1989,

Day.  1994. Evaluation of Add Generating Rock and Add Consuming Rock Mixing to Prevent Add
      Rock Drainage. In the Proceedings of the International Land Reclamation and Mine Drainage
      Conference and Third  International Conference on the Abatement of Acidic Drainage, April 24-
      29.                                            .

Devuyst, E.A.,  et al. 1990  (September).  Inco's Cyanide Destruction Technology.  Preprint No. 90-
      406.  Littleton, CO: Society For Mining, Metallurgy, and Exploration, Inc.

Dietz et al.  1994.  Evaluation of Acidic Mine Drainage Treatment in Constructed Wetland Systems.
      In the Proceedings of the International Land Reclamation and Mine Drainage Conference and
      Third International Conference on the Abatement of Acidic Drainage, April 24-29.

Doe Run Company. 1990 (February).  Fletcher Project:  Application for Metallic Minerals Waste
      Management Area Permit.

Doyle, F.M. (editor).  1990. Mining and Mineral Processing Wastes, proceedings of the Western
      Regional Symposium on Mining and Mineral Processing Wastes.  Berkeley, CA.  May  30-June
      1, 1990.  Littleton, CO: Society for Mining, Metallurgy and Exploration, Inc.
                                             7.3                              September 1994

-------
           	-_	:	.	EIA Guidelines for Mining
•lllM         IIIIIII IIIIIIIH     « IIIIIII III III ll|ll l|llllllllllllll|lllllll 111 11111,1 II Illlllllll l|lllllll||l Illllllllll IIII II   111  I II III  lllllllll III II  lllllllll  III 111(111|11111 lllllllll I lllll| IIIIIII 111 lllll|lllll IIIIIII 111 I II  IIIIIII I lllllllll II III III IIIIIII 11111)1)1 IIIIIII I 111 I lllllllll 111 II   l    ll||l

           Dunca^D.andC.Walden.  1975.  Prediction of Acid Generation Potential.  Report to Water
                Pollution Control Directorate, Environmental Protection Service, Environment  Canada
	!	4-	                  -                             "   '                          '
           Durkin,T.V.  1990. Neutralization of Spent Ore from Cyanide Heap Leach Gold Mine Facilities in
                Me Black Hills ofSouth Dakota -Current Practices and Requirements. AIME's Proceedings of
                the 4th Western Regional Conference  on Precious  Metals and the Environment,'Lead.  South
                Dakota.
                       	„	-^-	—aan

               \Redamation Program: 19774983. MN Dept. Nat. Res., Division of Minerals, St. Paul, ML

          Egeretal.  1994. Metal Removal in Wetland Treatment Systems. In the Proceedings of the
  ,            International Land Reclamation and. Mine Drainage Conference and  Third International
 I	gm«	mill ii|iii|i||iii iiiiin i fiXJSfK	8? *k* Abatement of Acidic Drainage, April 24-29.
 iiiiiiiiii 11 iiiiiii nil iiiiiiiiiiiii iiiiii i i|iiiii i iiiiiii 11                      '  	"	i	i	i	i	i	i	
          Engineering'andMining Journal.  1990 (January).  "Technology Turns Southwest Waste mto Ore "
 	YfiL	1S.1* PP. 41-44.            .              .
                                 ' '   i         ,  i ''                 ' '                 !
          Environmental LaW Institute, 1992 (November). State Regulation of Mining Waste:  Current State of
 «•              me Art.        • 	       .       ,                       ,.	:	 	
                       1  	'   .,(?.,  	  "  	i	,	: 	  '	,'-!,	'  i	I	'	'	:	
         fast, John L.  1988 (June).  "Carbons-in-Pulp Pioneering at the Carlton Mill."  Engineering &
                                                   •                    .  •   •       *   .  6
         SSSyyi. ^.^ M- Erickson. 1988. Pre-Mine Prediction of Add Mine Drainage. In:
              Dredged Material and Mine Tailings.  Edited by Dr. Wffiem Salomons and Professor oT
              ylnch Forstner. Copyright by Spnnger-Verlag.  Berlin, Heidelberg.

         Ferguson, K.D., and K., A. Morin.  1991.  The Prediction of Add Rock Drainage - Lessons From
              ^J2*556  & Second International Conference on the Abatement of Acidic Drainage
              C*}nferen<* Proceedings, Volumes 1 - 4, September 16, 17, and 18, Montreal, Quebec '

         F6it»P-  19?° ...... ^art*>: ............... "*** ..... Sacer ...... Gold
        ^erstenau»M. C., (editor).  1976. Flotation, Volume 2.  New York: Society of Mining Engineers.


                                       - 1992'  u^^ Mining: Mechanical Extraction Methods, 'in
                                               2nd Edition (HA. Hanma^ ed.).  Society for Mining
                  SSfEr and Exploration, Inc.  Littleton, CO.
                                               ............ 1986; ................ ^^ ...... 1±,^±: ....... W:H: .........

              .RL^8Q (Pe^mber). "Operating A Commercial-Scale Bioleach Reactor at the Congress
             Gold Property.''  Mining Engineering.
                                                    . 1983. Determination of Add Generation Rates in

                                                            Conference of Water Pollution
                                                   7=4                              September 1994
                                                                            i        i      i   ,
                                                                                    i

-------
  EIA Guidelines for Mining	 .     	References.

                                     \
  Harrelson, C.C., C.L. Rawlins, and J.P. Potyondy.  1994.  Stream Channel Reference Sites: An
       Illustrated Guide to Field Technique..  U.S. Department of Agriculture, U.S. Forest Service,
       Fort Collins, Colorado.

  Harty, D.M. and P.M. Terlecky. 1984a (February).  "Existing Wastewater Recycle Practices at
       Alaskan Placer Gold Mines", Frontier Technical Associates, Memorandum to B.M. Jarrett,
       U.S. EPA, Effluent Guidelines Division.

 Harty, D.M. and P.M. Terlecky. 1984b (February).  "Water Use Rates at Alaskan Placer Gold
       Mines Using Classification Methods", Frontier Technical Associates, Memorandum to B.M.
     . Jarrett, U.S. EPA, Effluent Guidelines Division.

 Hedin, Robert. S. and Watzlaf.  1994.  The Effects cf Anoxic Limestone Drains on Mine Water
       Chemistry. In the Proceedings of the International Land Reclamation and Mine Drainage
      Conference and Third International Conference on the Abatement of Acidic Drainage, April 24-
      29.                       .     .

 Hellier, William W. 1994. Best Professional Judgement Analysis for Constructed Wetlands as a Best
      Available Technology for the Treatment of Post-Mining Ground-water Seeps.  In the Proceedings
      of the International Land Reclamation and Mine Drainage Conference and Third International
      Conference on the Abatement of Acidic Drainage, April 24-29.

 Hittman Associates, Inc.  1976.  Underground Coal Mining: An Assessment of Technology.  Prepared
      for Electric Power Research Institute, Palo Alto, CA, EPRI-AF-219, variously paged.

 Holmes, K.W.  1981 (January).  Natural Revegetation of Dredge Tailings at Fox, Alaska.  In
     Agroborealis: 2639.                                                                    "

 Hood, W. and A. Oertel. 1984.  A Leaching Column Method for Predicting Effluent Quality From
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 Hurlbut, C.S., and C. Klein. 1977.  Manual of Mineralogy.  New York: John Wiley & Sons.

 Hutchinson, R.W. and J.D. Blackwell.  1984. Time, crustal evolution and generation of uranium
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 Idaho,  Division of Environmental Quality, Water Quality Bureau.  1993 (May 11).  Personal
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Jarrett, A.R.  (1983). Water Management, 5th Edition.

Kim, A. G., B. Heisey, R. Kleinmann,  and M. Duel.  1982.  Add Mine Drainage: Control and
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                                            7-5                             September 1994

-------
             References
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                                    n                      ||                    i     i    |
             Kruczynski, W.L.  1990. Options to be considered in preparation and evaluation of mitigation plans.
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            Jki*nj/*-*





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            Lapakko, K. 1990a.  Regulatory Mine Waste Characterization: A Parallel to Economic Resource
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            Lapakko, K.  1990b.  Solid Phase Characterization in Conjunction with Dissolution Experiments for
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           	I	:	:	:	-	•	;	s	-	:	      "-•	              i
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                           (	  Iiiii!

-------
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      Greenslade, and J.M. Barker (editors).  Littleton, CO:  Society for Mining, Metallurgy, and
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     Kathy Sertic and Joe Kissing, Science Applications International Corporation. Falls Church,
     VA.
                                            7-7                             September 1994

-------

      References
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                                                                                                         I'llililililiilllliilllll
      Nicholson, Ronald V.  1992. A Review of Models to Predict Add Generation Rates in Sulphide
           Waste Rock at Mine Sites.  Presented to the International Workshop on Waste Rock Modelling,
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-------
 EIA Guidelines for Mining   	.	                  -    References


       Land Reclamation and Mine Drainage Conference and Third International Conference on the
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     29, 1994.
                                           7-9                             September 1994

-------
            References
                                                                                EIA Guidelines for Mining
            Stanford, W.D., 1987 (April). "Amax Sleeper Mine Exceeds Expectations On All Counts As Low-
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    I'llilllill'illli'llll Wmm'l in                           lillllllllll |i|||iliiliiiiiiiiii|i|iii|iiiii iiiiillli in iiiiiiiiiii iii mi in mi iiiiiiiiiii |i iiiiiiiiiiii ill iiiiiiiiiii iiiiiiiiiii 11	i	111 in	ii i	i	in	iii|	i	i

            StiH^ater Mining Company. Undated. Stillwater Mining Company (company produced brochure).

            Sullivan, P. J. and A. Sobek.  1982.  "Laboratory Weathering Studies of Coal Refuse."  Minerals
   	,	                         	,	.,	,	,,,	           •                   .  (  ,  ,

   S^Hft'iJH!1 Jfi^^n^H-  197,6-  Uranium	Deposits.  Tatsch-Associates, Sudbury Massachusetts.
              'I      "        '  ' i,	'	'	;	!	'	'.	;	'	                 •.   	'	'	:""'	"""	
            Tenot, Carl.  1994.  Memorandum from Carl Tenut, State of Tennessee to Cheryl Espy, EPA Region
                 4.    "                      •                                     .                      •  "  •
           U.S.
                mull   ii i        i                       i     ii    H      i       ii       j     ~i
     Congress, Office of Technology Assessment.  1988 (September).  Copper:  Technology and
        —^f ---- f — ______ __ _ -— — ii> «•——-—• ^j — —-•»••»••• • ••••  ,_»«*• w -^-I'-'-ii-Tirianr-i-i y i  ^*\*LSLj^g *  .4 bW*W*VfrV
 8     Competitiveness. OTA-E-367.  U.S. Government Printing Office.  Washington DC.
            .................... : ...... fi ........................ :r!r; .............. •:. | ........  : .......................................... • .................................. ; ............. ;; ; .................... ; _^ • ; ..: ,  ' ......... : .....    .   .
U.S. Department of Agriculture, Forest Service.  1992. A Conceptual Waste Rock Sampling Program
     for Mines C^erating in ]^-/|fc ^^^ ^-"j^ a potential for ^^ Rock Drainage. Written
                      ffl11   Department of Agriculture, 'Forest Service, Ogden, Utah.
                               iiiiillli iiiiiiH   .       ....... i .............. i ............ i '" i ..... i ............... i ........................................... i ........................... if '"("i .................................... |i|ir ...................   1 1   .........       i    i
                              lip
           U.S. Department of Agriculture, Forest Service.  1993.  Add Mine Drainage From Mines on the
                National Forests, A Management Challenge. Program Aid 1505, p. 12.

           U.S. Department of the Army, Corps of Engineers.  1987.  Corps of Engineers Wetlands Delineation
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                                                              "        '           '
                    ..,..;  'i
         ................... __.__;:SE2_.__S_, ...... S
                                  i.  1978b. International Coal Technology Summary Document.
                                    '  '    " "      DC, JHCP/P-3885, 178 p.
                                                                '            '    i:':;iii	iiiirJiqiiiiiii!.	iifljiiiit":1	iiiiiiL	iii	'iv!	llMun	P'	|i|	i	!n1i!|iliil||||ii||!i	
                                                                                                                    ^	<	i
                           of Energy, Energy -Mormation Administration.,  1992. Uranium Industry Annual
                                                              uc-98, Wsshington, DC.
                                                                       	i	i	i	:•	
                          of Health and ^Human Services.'  1982 (April). Technological Feasibility of Control
                                                                       0'  Washmgton, DC.
iiiiiiiiiiiiiiiiiniiiiiii        i|wniiiniiB
^-==_-!	0.S. Department of the Interior, Bureau of Land Management. 1992.  Solid Minerals Reclamation
                                       , Bureau of Mines.  1968. A Dictionary of Mining, Minerals, and
                             	Washington,	D.C.	"	
             •'•-'•YT-C—-~~~- — ~*~r***~iw*» **«M.W«M. vi xTiiiisS.  1977. Capital and Operating Cost Estimating
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                          °-— ..... licrisr, Bureau, of Mines.  1978. Processing Gold Ores Using Heap
                         ....... -— .....               ,         .      .
               "J^ach-Carbon^Adsprption Methods.  Information Ckcular No. 8770. Washington, DC.
                                                     i i  i   ii
                                                       I lillllllllll III lllll |i|||lll(i|||||(lllllllll llllllllilllllillB     111 111 111 lillllllllll 111 il|||ii|llli|l|l III (i I 11 "in lillllllllll	Ill 11 111 Ii lillllllllll
                                                                                                    111
                                                          	I  	I  I"    	     I	I	
                                                       7-10
                                                                              September 1994
••^^^
                                    III ...... (i Illllllliiiillllllilll lllltlliiillililillliilil'l'i Milll HIVIIi ...... Ill i III I lllidlliill ....... ill
                                                                        	"in'in iiiiiiNiiiiiiiiiii ii in	liw           	PI   'iiiiii	in
                                                                                                  iiv   	ii" iilil
                                                                                                  	[	ji

-------
 EIA Guidelines for Mining	                           References


 U.S. Department of the Interior, Bureau of Mines.  1979.  Environmental Assessment of In Situ Leach
      Mining, Final Report; Prepared by PRC Toups and Mountain States Research and
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      Minerals Availability Open File Report, by L.V. Coppa.  Washington, DC.

 U.S. Department of the Interior, Bureau of Mines.  1985.  "Gold" (by J.M. Lucas). In Mineral
      Facts and Problems,  1985. Washington, DC:  GPO.

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     Metals and Industrial  Minerals Industries" (by A.O. Tanner).  In 1988 Minerals Yearbook,
     Volume 1:  Metals and Minerals.  Washington, DC

U.S. Department of the Interior, Bureau of Mines.  1990c.  "Gold" (by J.M. Lucas).  In 7959
     Minerals Yearbook. Washington,  DC:  GPO.
                                           7-11                             September 1994

-------
	i	i	'"References
                                                                           EIA Guidelines for Mining
          U.S. Department of the Interior, Bureau of Mines.  1992a.  "Gold 1991 Annual Report" (by J.M.
               Lucas).  Published in Washington, DC.
          U.S. Department of the Interior, Bureau of Mines.  1992b.  "Iron Ore." |n Mineral Commodity
         	iSummarieSf	|S92(by P.H. Kuck). Washington, D.C.  "'
          U.S. .Department of the Interior, Bureau of Mines.  1991a (May).  "Mining and Quarrying Trends in
               the Metals and Industrial Minerals Industries" (by A.O. Tanner). In 1989 Minerals Yearbook.
               Washington, DC:  GPO.
I'!!!!!	      U.S. Department of the Interior, Bureau of Mines.  1991.  Submarine Disposal of Mill Tailings from
                                   Overview and Bibliography. An Overview and bibliographic
          iiii
               CoropUation of References on the Biological,, Chemical, Environmental, and' Technical Aspects.
                 lDL ........ laerl ..... GJE ........ Sherman, and P'DT ....... pling; .............. QER ..... 89-921 [[[ T [[[
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	Published in "Washington, DC.                 .               "          "  .

    ;;z.~=U.S. Department of the Interior, Bureau of Mines. 1993b. 1991 Copper Annual Report (by Janice
           *   Jolly). Washington, DC.                              .
         U.S. Department of the Interior, Bureau of Mines. 1993c.  Platinum-Group Metals 1992 Annual
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         U.S. Department of the Interior, Bureau of Mines. 1993d.  Tungsten 1992 Annual Report.
        ............................................ ' [[[ ' ............................................... "                             iiiii ....... ijlllinilii ......... i « ......... #\i iii|l!lill|iqiqilnlliili|jli!ii!|!ili|iihi|:!lili!"i| ................ illl .....
                                                                 iiii ill ..... - ........ iniil ..... ; . 'liijiiiiillll
         U.S. Department of the Interior, Bureau of Mines. 19936. Molybdenum 1992 Annual Report.
                                                           - ]*tanium l_99^_Anmal 'Report.
         U.S. Department of the Interior, Bureau of Mines. 1993g.  Vanadium 1992 Annual Report.
         U.S. Department of the Interior, Bureau of Mines. 1993h. Aluminum, Bauxite and Alumina 1992
              Annual Report.
         U.S. Department	of the	Interior,	Bureau of Mines.	1994*	International Land Reclamation and Mine
                      	-	-———	_=~_,.	_____=_	,———~™	
      	Proceedings of a conference held in Pittsburgh, Pennsylvania, April 24-29, 1994.  Bureau of
      	:	• r	 Mines Special Publications SP 06A-94 through SP 06D-94. 4 volumes.  '
                                             of Mines.  Undated(a).

-------
  EIA Guidelines for Mining    	'	                       References


  U.S. Department of the Interior, Geological Survey. 1973.  "Copper".  In United States Mineral
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       Reston, VA.                                   .

  U.S. Department of the Interior, Geological Survey. 1973.  "Gold."  United States Mineral
       Resources. Professional Paper No. 820. • Reston, VA.

  U.S. Department of the Interior, Geological Survey.  1973a.  "Iron." In United States Mineral
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       Reston, VA.

 U.S. Department of Interior, U.S. Geological Survey. 1977. National Handbook of Recommended
       Methods for Water-data Acquisition/Prepared Under the Sponsorship of the Office of Water Data
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 U.S. Department of Interior, U.S. Geological Survey. 1990. Water Resources Investigations Report.
       Blevins.  No.90-4047.  Reston VA.

 U.S. Environmental Protection Agency. 1973. Processes, Procedures, and Methods to Control
      Pollution from Mining Activities. Washington DC, DOE/EPA-430/9-73-011, 390 p.

 U.S. Environmental Protection Agency. 1975. Coal Mining Point Source Category.  Washington
      DC. Federal Register 40 202 48830-8.

 U.S. Environmental Protection Agency, Office of Water and Hazardous Material;  1976a.
      Development document for interim final effluent limitations guidelines and new source
      performance standards for the coal mining point source category. Washington, DC EPA
      440/1-76/057-a, 288 p.

 U.S. Environmental Protection Agency, Industrial Environmental Research Laboratory.  1976b
      (June).  Metals Mining and Milling Process  Profiles with Environmental Aspects.  Prepared by
      Battelle Columbus Laboratories for U.S. Environmental  Protection Agency.  NTTS Publication
   .   No. 256394.  Washington, DC.

 U.S. Environmental Protection Agency. 1978a. Add Mine Drainage and Subsidence:  Effects of •
      Increased Coal  Utilization. Washington DC, EPA-600/2-78-068, 141 p.

 U.S. Environmental Protection Agency. 1978b.  Site Selection and Design for Minimizing Pollution
     from Underground Coal Mining Operations.. Washington DC, EPA-600/7-78-006, 98 p.

 U.S. Environmental Protection Agency.  1979.  Assessment of Environmental Impact of the Mineral
     Mining Industry•, Prepared by PEDCo Environmental, Inc. EPA-600/2-79-107.  Washington
      DC.

U.S. Environmental Protection Agency, Office of  Water, Effluent Guidelines Division.  1982 (May).
     Development Document for Effluent Limitations Guidelines and Standards for the Ore Mining
     and Dressing Point Source Category.  EPA 440/1-82/061. Washington, DC.
                                           7-13                             SeptembftT 1994

-------
            References
                                                                      EIA Guidelines for Mining
    U.S. Environmental P^rotection Agency.  1984 (December).  Overview of Solid Waste Generation,
         Management, and Chemical Characteristics. Prepared for U.S. EPA under Contract Nos. 68-
	03*3197, PN 3617-3 by PEI Associates, Inc.'
                                              '
    U.S. Environmental Projection Agency, Office of Solid Waste.  1985 (December).  Report to
         Congress -Wastes from the Extraction and Benefidation of Metallic Ores, Phosphate Rock,
         Asbestos, Overburdenfrom Uranium Mining, and Oil Shale. EPA 530-SW-85-033.
         Washington, DC.         ,                                                             .
  •
    U.S. Environmental Protection Agency. 1986. Quality Criteria for Water. REPA 440/5-86-001.
         Washington, DC.

    U.S., Environmental	Pjpecj|pj|iii;Agency, Office, of Water. 1988a(May).  Development Document for
       I  fsffj'ttffflf EtJrRitQtJQfls Gnf^€lJT^€s ofui Nsw Source P.€ifoTiH(Xfice StofiuctTos for the Ore Animus QTICI
   ,     Dressing Point Source Category:  Gold Placer Mine Subcategory (Final Draft). Washington,
    	in	i|iii«DC. 	                                          '	]	[	[	,	[	

    U.S. Environmental Protection Agency. 1988b. Economic Impact Analysis of Final Effluent
     ,.    GitideUnes	and	Standards for the Gold Placer Mining Industry. Office of Water Regulations
         and	Standards.	Washington,	DC.   "                   .
    iiiiiiiii
           U.S. Environmental ....... Protection ..... Agency. 1989a. Final Report:  Copper Dump Leaching and
      ......     Mcmagement Practices that Minimize the Potential for Environmental Releases.  Prepared by   '  '
                              .......    .....       ....... - ........   ......      ...... ____-_. ...... _.._. ....... ___ ...... ___, ...... „ ................ _____ [[[
        PEI Aijsocliiitesi ....... j
        Washington, DC.
                                                     ^ ...... ____-_. ...... _.._. ....... ___ ...... ___, ...... „
           U.S.	Environmental	Protection Agency. 1989b. Rapid Reassessment Protocols for Use in Streams
                ana Rtvers.
                     PA/440/4-89/001. Washington, DC.


   U.S.	Environmental	Protection Agency.  1989c.  Ecological Assessment of Hazardous Waste Sites: A
  	"'--	______     		
          :,U.S.j	Ejmroi|nen|i|	gro|ec||gnaAgency. 1990 (January). Performance of Current Sediment Control
                                   " Construction Sites.  Metropolitan Washington Council of Governments.
    ;=                                       	1990	(AprD)!
	=!	,	=	^	,	U.S.
                Inventory of Current Practices. Washington, DC.
        Ejrvjronmental	Protectian	Agency,	Office	oflUseaxch	and^Deydppmeit^	19921'' Draft.	
                        Generation From Non-Coal Mining Waste:  Notes of July 1992 Workshop.
                 for	the	Environmental	Monitoring Systems Laboratory, Las Vegas,'Nevada 89193-  '
          U.S. Environmental Protection Agency, Office of Research and Development.  1993 .(May 20).
               Personal cojnnumication between Ed Heithmar, U.S. EPA Office of Research and Development,

-------
 EIA Guidelines for Mining	                References


 U.S. Environmental Protection Agency.  1994.  Workshop on the Use ofSulfate Reducing Bacteria.
      for Treating Mine Drainage from Metals Mines.  Cincinnati, OH,  February 23-24,  1994.

 U.S. General Accounting Office. 1991(June). Mineral Resources: Increased Attention Being Given to
      Cyanide Operations. Report to the Chairman, Subcommittee on Mining and Natural Resources,
      Committee on Interior and Insular Affairs, House of Representatives. GAO/RCED-91-145.

 U.S. Soil Conservation Service. 1975.  Procedure for Computing Sheet and Rill Erosion  on Project
      Area. Technical Release No. 51.

 United States Steel. 1973.  The Making, Shaping, and Treating of Steel (H.E. McGannon, editor).
      Herbick and Held, Pittsburgh, PA.

 University  of California at Berkeley. 1988 (July).  Mining Waste Study, final Report. Prepared for
      the California State Legislature. Berkeley, CA.

 University  of Nevada - Reno.  1993 (January 13).  Personal communication between den Miller and
      Joseph Rissing, Science Applications International Corporation. Falls Church, VA.

 van Zyl, D J.A., I.P.G. Hutchison, and J.E. Kiel (editors). 1988. Introduction to Evaluation,
      Design and Operation of Precious Metal Heap Leaching. Projects.  Society for Mining,
   * .Metallurgy,  and Exploration, Inc. Littleton, CO.       .

 Want, W.L.  1990.  Laws of Wetlands Regulations. Clark Boardman Company, Ltd. New York,
      NY.                                                             -

Weiss, N.L. (editor).  1985.  SME Mineral Processing Handbook,  Volume .2.  New York: Society
      of Mining Engineers.           .            *         .                   .

White, William W. et al.  1994.  Chemical Predicative Modeling of Add Mine Drainage. From Waste
     Rock: Model Development and Comparison of Modeled Output to Experimental Data.  In the
     Proceedings of the International Land Reclamation and Mine Drainage Conference and Third
     International Conference on the Abatement of Acidic Drainage, April 24-29.

Whiteway,  P. (editor). 1990.  "Mining Explained: A Guide To Prospecting and Mining." The
     Northern Miner.

The Wildlife Society, 1980.  WiIdlife Management Techniques Manual. Fourth Edition: Revised.
     Sanford D. Schemnitz (editor).  Washington, D.C.

Williams, R. David.  1994.  The Bureau of Land Management Add Rock Drainage Policy  An
     Evolution in Environmental Protection. In the Proceedings of the International  Land
     Reclamation and Mine Drainage Conference and Third International Conference on the
     Abatement of Acidic Drainage, April 24-29.

Wyoming Department of Environmental Quality, Land Quality Division.  1991.  In Situ Mining State
     Decision Document for Everest Minerals Highland Uranium, WDEQ/LQD Permit No. 603-A2.
                                           7-15                             September 1994

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SECTION 6




GLOSSARY

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                                     GLOSSARY
                                                                               -

                                                                           do not
        which, thefcie, an EA •    . E                °n fc human "vuo.meM and for
ENVIRONMENT IMPACT ASSESSMENT-  Environmental impact assessment is

      pflL2S*TiatlC' re]foducible' a™1 interdisciplinary consideration of the potential
      effects of a proposed action and its reasonable alternatives on the physical, biological

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                    of activities related to projects, plans, programs or policies. Involvement of the public
                    and interested parties is important to obtaining complete information on impacts and
              	'ensunng sound results.
                           Jl '         '    ,                    .      ',•','''

                    EIA has a variety of names in different settings.  It may be a formal document or
                    dispersed in different parts of other documents. In more recent training materials,
     	,	,	I	,	i,	ESSJA	h,32	SlEPPP6** anv distinction between the term environmental assessment (EA)
                    and environmental impact assessment (EIA) to simplify discussion. However the
                    original Sourcebook from which Section 1 is drawn may use US terminology, that is
                    3EA	|J2E	|fee,	IlIlM	assessment	of	whether	a.	fujl	EM	|§	needed,  andi EIS  for an
                    environmental	impact	statement	or	full EIA	document.	You may also see the original
                               use the |erm eQyy-onjnentai assessment (EA)  for pie process and
                    environmental impact assessment (EIA) used to refer to the document.
                     SK .ASSESSMET ~
                                                                    TlSfc assessment deals with risks
                   feat	anse	in	or	are	transmitted	through	the	airz	water_j	soil	or	biological food chains to
                   man,	                                     	


                   and' interested parties.
                       l,i: ................. II ..... a ................................ ...... „!: ................................. f,
                                                      task that depends on the application of human
                                    ....... JfeSffiSSSpg ....... the ....... significance -of the potential impacts to the affected
                                       " [[[
                            —   mpartmejital models that estimate fee relative distribution of pollutants
                                       OTmpartments (e.g., air, sol, water, sediment, biota).   These
                             based ....... on ...... the ...... tendency of a chemical to escape from one chemical phase into
                     	gg,	NO	;SJG|gFICANT	IMfACT	(FNSI) — A	document briefly presenting fee
                  ; jeasons	why a proposed g^gon jfifa not have a significant effect on fee environment and
                   iB^anEXAwiU	ngl	^prepared.	

                           njeda; ..... Xknown as
                                                                   fiS ..... transfers ....... ochemicals ..... among
                                              exposures from multiple environmental
               Most multi-compartment models consist of linked, suigle-medium models,
                       i piay simulate fee physical and chemical processes  feat drive fee transport of
                       icals across air/water, air/snii  anH water/soil	mterfaces.	The	dala.requirements for
                                                            understanding  of intermedia
     sucn models  are

                  processes is still embryonic.
                                          effects are those caused by an action that are later in time or
                                 in	distance;	but	that	are	still	.reasonably foreseeable (e.g., development
                                                                                   iJH^                  	Illlllll
                                arenas as a result of road building for logging purposes.

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 NON-GOVERNMENTAL ORGANIZATION               *

U.S. ENVIRONMENTAL ASSESSMENT (EA) - Li the U S
U.S. ENVIRONMENTAL IMPACT STATEMENT fPJ^  T« th- TT c    ™ .

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           SECTION 7

ENVIRONMENTAL IMPACT ASSESSMENT
RESOURCES ON THE INTERNET AND ON
          COMPACT DISC

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7. INTERNET SITES AND INTERACTIVE CD-ROMS FOR REFERENCE

In addition to the written hard copy materials presented within this resource manual and referred to hi
the student texts, reviewers may take advantage of a burdgeoning number of on-line internet services
related to Environmental Impact Assessment and an interactive CD-ROM with both resource materials,
a self-study case study to prepare an environmental impact assessment and also to provide logical and '
ordered prompts in the review or preparation of any future EIA.  EPA capacity building materials
are now available off the EPA website at www.epa.gov/oeca/ofa.

7.1    Sample Internet Site References Related to Environmental Impact Assessment


      1.     AUSTRALIAN EIA NETWORK - ENVIRONMENTAL IMPACT ASSESSMENT"
            (EIA) IN AUSTRALIA - COMMONWEALTH
            http://www.erin.gov.au/portfolio/epg/eianet/eia/eia_com.html
      2.     BRITISH COLUMBIA ENVIRONMENTAL ASSESSMENT OFFICE
            http://www.eao.gov.bc.ca/
      3.     CANADIAN ENVIRONMENTAL ASSESSMENT AGENCY
            http://www.ceaa.gc.ca:80/agency/agency_e.htm
      4.     CffiSIN HOME PAGE
            http://www.ciesin.org/
      5.     DEPARTMENT OF ENERGY ENVIRONMENTAL POLICY AND GUIDANCE -
            RISK ASSESSMENT (US)
            http://tis-nt.eh.doe.gov/oepa/guidance/risk.htm
      6.     DEPARTMENT OF ENVIRONMENT - ENVIRONMENTAL GUIDELINES
            (MALAYSIA)
            http://www.jas.sains.my/doe/r_guide.html
      7.     DIRECTORY OF ENVIRONMENTAL RESOURCES ON THE INTERNET
            http://www.envirosw.com/
      8.     ECOLOGICAL MONITORING AND ASSESSMENT NETWORK (ENVIRONMENT
            CANADA)
            http://www.cciw.ca/eman-temp/intro.html
      9.     EIA (ENVIRONMENTAL IMPACT ASSESSMENT) CENTRE, UNIVERSITY OF
            MANCHESTER
            http://www.ids.ac.uk/eldis/data/d021/e02168.html
      10.    EIA: ENVIRONMENTAL IMPACT ASSESSMENT IN A TRANSBOUNDARY
            CONTEXT - PRINCIPLES AND CHALLENGES FOR A COORDINATED NORDIC
            APPLICATION OF THE ESPOO CONVENTION, BY STIG ROAR HUSBY
            http://odin.dep.no/eia/paper/srh980516.html
      11.    EIS (ENVIRONMENTAL IMPACT STATEMENT) DATABASE
            http://envirosense.com/ofaview/one_search.html
      12.    ENVIRONMENTAL IMPACT ANALYSIS DATA LINKS
            http://h2o.usgs.gov/public/eap/env_data.html
      13.    EUROPEAN ENVIRONMENT AGENCY
            http://www.eea.dk/default.htm
      14.    GEO-1,THE COMPLETE REPORT: TABLE OF CONTENTS - LIST OF FIGURES
            - LIST OF TABLES
            http://www.grida.no/prog/gIobal/geol/ch/toc.htmMgs
      15.    GEO INFO SYSTEMS RESOURCE PAGE

                                      7-1

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           f
	I	http://www.geoinfosysteins.com/resource.htm


                 16.     ffiEE-SSrr (ELECTRICAL AND ELECTRONIC ENGINEERS - SOCIETY ON
•111 iiiii ••iiiiiii ill ill
     17.
                                                        FOR IMPACT ASSESSMENT
                            //ndsuext.nodak.edu/iaia/
                                                   FOR THE SYSTEMS SCIENCES HOMEPAGE
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                 19.
            ISEM (INTERNATIONAL SOCIETY FOR ECOLOGICAL MODELING)
            http://ecomod.tamu.edu/%7Eecomod7isem.html
     20.     THE PERRY-CASTANEDA LIBRARY MAP COLLECTION
	,	i	i	http://wwvv.lib.utexas.edu/Libs/PCL/Map_collection/map_sites/map_sites.ht
|™^                                                       	ACT	(TJSA)	;	\	\	
	:	;	http://ceq.eh.doe.gov/nepa/nepanet.htm
S5S2&   	ASOCIAL AND ENVIRONMENTAL ASSESSMENT BULLETIN
            http://home.echo-on.net/~lisa/bulletin.html
 ==33.     THEWATERSHED MANAGEMENT COUNCIL
                        http://glinda.cnrs.humboldt.edu/wmc
               1^4.	\	US EPA, OFFICE OF FEDERAL ACTIVITIES
                   =-:=littp://es.epa.gov/oeca/of
                                     111 111 111 111 l in III lli 111 ill	Ill I lillli lllllll	I Illllill ill ill	I I ( I 11II ill* III I'll II i 1 illlllllllllllllllll in 111 1 (111 111' lllllili Ililllli i Iiiii 1 lull  Hi I liiil I  11 "II11 1i lllllll illllllll 11 lllllll 11 illllll • il 11"	Ill
                 Eteractive CD-Rom: References:
                 USEPA has produced two compact discs that are either available separately or combined into a
          single CD in version 4 issued in 1998. The two component programs are:
                 = liYgonmental Impact Assessment Resource Guide (EARG): The EARG is an interactive
                            allows participants to walk through information on the EIA process from project
                'Initiation to post-decision analysis.  The outline of its contents follows in this section.
                iiiii aiiiiiiH^^^^                      J
                 -  Environmental Impact Assessment Interactive Case Study: Chuitna, Alaska: This interactive
                 CD-ROM enables the user to wajk through the complete EIA process for a proposed project in
                 Chuitna, Alaska and develop their own EIA.  The CD-ROM covers the project's initiation,
                   Sping, generation and analysis of alternatives, decision-making, and post-decision analysis.
                        ebook feature of the program Is geared toward both si^tudy is well as anprbyidhig
                          ;tooll As an ongoing ...... tool] ....... the" ..... noteBook' ..... leature ..... of ""the ..... programenables ....... SieuseTto ...................
                                as	a, prompt to assist in fine development or review or any EIA shice thejr can
                 be cleared and saved under different file names.  An outline of the program's contents follows
                 in this section..
              —;. Copies" can be obtained from:
                                    of Federal Activities
                              U.S. Environmental Protection Agency
                              MC	2251-A	
                                                                    ^^                           	llflil llllll
          	I	
                               1200 Pennsylvania Avenue NW
                               Washington D.C. 20460

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              ENVIRONMENTAL .ASSESSMENT RESOURCE GUIDE (EARG)

        The focus of the EARG software is generally an Environmental Assessment (EA) process
  for project level decisions.


        There are six steps in the HA process: 1) Initiation, 2) Scoping, 3) Generation of
  Alternatives, 4) Assessment, 5) Decision-Making and 6) Post Decision Analysis (Follow up
  project monitoring).


        INITIATION involves the review of the environmental information packet provided by
  those proposing the project, determination of the extensiveness of the project, assembly of an
  interdisciplinary team, and development of a public involvement strategy.


     •   SCOPING involves the identification of reasonable issues and concerns, consultation
  within and among governmental departments, and scoping meetings that involve the public.

        GENERATION OF ALTERNATIVES involves the identification of alternative ways to
 meet the basic purpose of and need for the project.


        ASSESSMENT involves an inventory of existing environmental conditions, assessment of
 the potential environmental impact of the project, and determination of the steps required to
 minimize the environmental damage.


       DECISION-MAKING involves making the decision based on the Final EA documentation
 and formally documenting the decision publicly.


       POST- DECISION ANALYSIS involves the evaluation of scientific, technical,
 procedural, and administrative issues during and after implementation of the proposed'action and
 performance of base-line compliance, environmental effects, and mitigation monitoring.
 (For ease in navigating on the computer through EARG use the structural outline that follows the
 Chuitna case study description).


                           CHUITNA CASE STUDY

       The Diamond Chuitna Coal Case Study is based on an actual Environmental Impact
 Statement (EIS) conducted by Region 10, USEPA in the late 1980's  and is designed to provide a
 computer tutorial experience in simulating the development of a complex project proposal that
 required the preparation of an EIS.


       The proposed project involves the development of a coal mine in Beluga Region of
 Alaska, USA. Throughout the software program, the user plays the role of the Project Manager
 and is responsible for making plans and decisions. The program will be most meaningful if the
user has already worked through EARG.
                                         7-3

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	!	"	'	I	''	!	
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                               CD-ROM: ENVIRONMENTAL
                       ASSESSMENT RESOURCE GUIDE (EARG)
=;i::z ::"': ..... :::,,,; ....... :::;::: ...... ™," ...... :::::::;: OUTLINE OF CONTENTS
         r.:« ....... , ........... l INTRODUCTION
         :•--	•	-	i	&	ASffiffiEs	
           ft'pnmD,	Glossary
                         igs PIans]&	Programs
                    . References
                                      lilllii'	Ill	IHB^^^^^^^^^^^^^^
                     "onrnentalnformatinPacket
f^^^J^pject Responsibilities
         jlic Involvement Strategies
                            °	'	M,
     >,	FJanning Records
 B. Tools
                                                                              ii'li.l'Tli'illLJllllllllllillillli'i'li'iBii	l":lli "IIHillilWihJII
   i=^^^              	Issues	
                      1. EA and Project Planning
   .,	,	;	,.,	;,;,,,,,!	,	.;	,	y	,;	2.	Goordjriatioji.witli	Other, Laws	
                                        !il!!K^^^^^                     ..... iisi
                                                                               ........ lillM^     ..... Ill ..... 11!
                      1. Needs
               	,	.,2r:Tools
       ^	r^ri'lr:;!^'!. Issues
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                • Project Information
       Early Planning
                                                     7-4

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           3. Public Involvement
       B. Tools (Scoping meeting)
       C.Issues
       D. Linkages
       E. References

V. GENERATION OF ALTERNATIVES
       A. Needs
       B. Tools
       C. Issues
       D. Linkages
       E. References
       F. Describing the Environmental Setting
           Geology, Topography, Soils, Groundwater Resources, Surface Water Resources,
           Terrestrial Communities, Aquatic Communities, Sensitive Areas, Air Quality, Land
           Use, Demography, Sound Levels, Infrastructure Services, Transportation, Cultural
           Resources, Project Economics.

VI. ASSESSMENT
       A. Affected Environment
           1. Needs
           2. Tools
           3. Issues
           4. Linkages
           5. References
           6. General Site Information (12 items, most illustrated)
       B. Impact Identification
           1. Needs (17 illustrated items)
           2. Tools
              a. Site Visits
              b. Use of Checklists
              c. Checklist Example
              d. Matrix
              e. Networks
              f. Other Tools (GIS)
           3.Issues
              a. Boundaries
              b. Predicting Impacts
              c. Assessing Cumulative Impacts
              d. Defined Endpoints
          4. Linkages
          5. References
      C. Impact Analysis and Prediction
           1. Needs
          2. Tools

                           -        -      7-5

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            II           I III   II

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                      3,Issues
              	4,	Linkages
                      5. References
                 D. Determination of Significance
              	!'""!	Seeds	
                      2. Tools
                      3: Issues
                      4: Linkages
                      5, References
                      6. Categories of Mitigation
                          a. Avoidance
                          b. Minimization
                          c. Rectification
                          d. Reduction
                 	e. Compensation
                 'F. Documentation
                      LNe^ds
                      2. Tools      ™"™'"
                      3. Issues
                      4. Linkages
                      5. References
                      6. EIA, Elements
                 G. Small Projects
                      1, Small Project EIAs
                     2. Environmental Audits
                 H. World Bank Mitigation Tables
                     Ch. 8: Agricultural and Rural Development, Rural Development, Agroindustry,
                     Dams and Reservoirs, Fisheries, Floo3 Protection, N*atural Forest Management,
 i •"''i™, j'i'ij' 's> i! I] • jr.™•IfflffiSSi?i?v^0^mei^^nf *^ore^a^°.?',fr^s^0™an<^.•P1-3^^,6,1? Hy,^?9^.^^
 ™	'l'"1""1'	'""'	^^'^"'"'.Jii^eland Management	Rural	roact'sT'
                     Cff. 9: Population, Health, Transport, Development, Water and Sewer, Roads and
                     Highways, Inland Navigation, Ports and Harbors, Housing Projects, Solid Waste,
                     Tourism, Wastewater.
                     QL !i!:"/~O

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      D. Linkages
      E. References
      F. Alternatives (Matrix)

VIII. POST-DECISION ANALYSIS
      A. Needs
      B. Tools
      C. Issues
      D. Linkages
                                       7-7

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                       	riii""!1:	
             	I	

                 CD-ROM: EIA CASE STUDY: CHUITNA, ALASKA
            d	,	,;	
                         ::	:	::=	!	OUTLINE OF CONTENTS
                                                                              ll nililiV! , iliilllllliilPHIIi',!,1!1!! I Ilii:!1: '< ;«lllilil|i|lilllllllllllllinill
-------
       5. Determination of Significance
           a. Introduction
           b. Criteria for Significance
           c. Magnitude/Likelihood
           d. Confidence in Prediction Values
           e. Assumptions/Limitations
       6. Mitigation
           a. Introduction
           b. Reclamation Plan
           c. Categories of Mitigation
           d. Terrestrial Habitat
           e. Test Your Knowledge
       7. Documentation

E. DECISION-MAKING

       1. Introduction
       2. Review Proposed Tradeoffs
       3. Identify Preferred Alternative
       4. Comparing Housing/Airstrip Options
       5. Record of Decision
       6. Status of Report

F. POST-DECISION ANALYSIS

       1. Introduction
       2. Important Impacts
       3. Categories of Mitigation
       4. Monitoring Requirements
                                          7-9

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                  Example Internet Site References Related
                                     to
                      Environemental Impact Assessment

 SOCIAL ANDENVIRONMENTAL ASSESSMENT BULLETIN
       http://home.echo-on.net/~hsa/bulletin.html

 ENVIRONMENTAL IMPACT ANALYSIS DATA LINKS
       http://h2o.usgs.gov/public/eap/envjiata.ntml

 ISEM (INTERNATIONAL SOCIETY FOR ECOLOGICAL MODELING)
       http://ecomod.tamu.edu/%7Eecomod/isem.html

 INTERNATIONAL SOCIETY FOR THE SYSTEMS SCIENCES HOMEPAGE
       http ://www. sysval. org/isss/

 INTERNATIONAL ASSOCIATION FOR IMPACT ASSESSMENT
       http://ndsuext.nodak.edu/iaia/

 IEEE SSIT HOME PAGE
       http://wvm4.ncsu.edu/unity/users/5y5herkert/index.html

 DOE ENVIRONMENTAL POLICY AND GUIDANCE - RISK ASSESSMENT (US)
      http://tis-nt.eh.doe.gov/oepa/guidance/risk.htm

 CANADIAN ENVIRONMENTAL ASSESSMENT AGENCY)
      http://www.ceaa.gc.ca:80/agency/agency_e.htm

 BRITISH COLUMBIA ENVIRONMENTAL ASSESSMENT OFFICE (EAO)
      http://www.eao.gov.bc.ca/

 ECOLOGICAL MONITORING AND ASSESSMENT NETWORK (ENVIRONMENT
 CANADA)
      http://www.cciw.ca/eman-temp/intro.html

 THE WATERSHED MANAGEMENT COUNCIL
      http ://glinda. cnrs.humboldt. edu/wmc

DIRECTORY OF ENVIRONMENTAL RESOURCES ON THE INTERNET
      http://www.envirosw.com/

CIESIN HOME PAGE (Not able to be contacted during test run)
      http://www.ciesin.org/


                                   7-11

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          "  I	
   	EUROPEAN ENVIRONMENT AGENCY
   IIIIIIVB	          http://www.eea.dk/default.htm
                                                 ii in iii innn Hi iiiiiiiivi ifn'my
      	I	
          EIA:ENVIRO3S!MENTAL IMPACT ASSESSMENT IN A TRANSBOUNDARY CONTEXT -
      	;	;	PRINCIPLES	AND	CHALLENGES	FOR	A	CQOJ^MATED	NORDIC APPLICATION OF
          THEESPpO CONyENTION, BY STIGROARHUSBY
                htto:7/odin.dep.no/eia/paper/srh980516.html
         •MlANCHESJgk	[
                 =_*H^^

          ApSTRALIANEIANETWOEK - ENVIRONMENTAL IMPACT ASSESSMENT (EIA) IN
          AUSTRALIA - COMMONWEALTH
=—^
                nttp://www.jas.sains.my/doe/r_guide.ntml -
AP-RELATED
                                 S THE PEj^Y-CMTAlfeDALrBRAJlYMAP COLLECTION,
                                               ^  '  ^   ^ '  ^  ^         .
                                .edi^
               INFO SYSTEMS RESOURCE PAGE
  --
                                              QF CONTENTS -..LIST OZMGURES -.LJST OF
                         '^Sa.no/prog/gfobaFgeo l7
                                               ill!	I!?	|:
                                     *.f,fc-l'«lf'±	MCWIBi4VEMrfW
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